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DEC
02
2020

plywood underlayment expansion gap

Hand sanding is not sufficient. joist spacing interior dry or wet areas Limitations minimum 2" … Also, any tips on explaining this to my contractor? As you install the pieces, move them away from the wall and tighten the joints out “in the field.” When the pieces fit and the joints are tight, tack them in place with a ring-shank nail or with the staple gun. Assuming that plywood expands and contracts enough to make this an issue (and please correct me on that if it is an incorrect assumption), should I leave a gap between the sheets of plywood to account for expansion and contraction? joist spacing, single layer OSB or plywood subfloor Areas of Application over any even and structurally sound OSB or plywood subfloor with 16" (406 mm) o.c. If you do not leave an expansion gap, your floor will try to expand but will have no space, resulting in it warping or lifting up. the thickness of a nickel, between each panel. The distance of the gap can be maintained by inserting spacers made of off-cut timber. Do this by multiplying the room’s length by its width. For a SurePly ® plywood underlayment installation without an expansion joint, lightly butt the panels together without applying any pressure so they barely touch at the joints.The second method is to install the SurePly ® plywood underlayment panel with an expansion joint and using a seam filler. After sanding, the seam filler should fill the seams and be flush with the edges of the. Not only that, but fixing down prevents this too. This reminds me of something I've wondered for a while... if the sheathing is exactly 4'x8' and the studs are spaced exactly 16" or 24" OC, then don't the 1/8" gaps accumulate after a few sheets and cause them to stop aligning with the center of the studs? Patriot Timber Products, Inc.117 S Westgate DriveGreensboro, NC 27407Fax: 336-299-4050, Better Alternative than Lauan and Meranti Plywood, Meranti Plywood / Lauan / Luan vs. RevolutionPly®. It takes 36' (nine 4' panels, 8 gaps) of wall before the panel creep has moved a full inch, which is probably the absolute limit. Insert shims to create about a 1/4-inch to 3/8-inch gap between the flooring and the walls. Does the subfloor need the expansion joint as well? The "plywood underlayment,subfloor sandwich" that you mentioned having to have the "movement joint" -you are talking about the second layer of plywood and not the sub floor, right? Right side up. Just as important is to make sure you have an adequate gap around the outside for the hardwood, follow … Some framers "creep" their layout to compensate. Unfortunately, the APA video (below) doesn't answer the stud-spacing question. Start from a panel corner and fasten row by row to the opposite side. Plywood manufacturers are aware of these problems. On a building this small, is it necessary to allow expansion gaps between the plywood sheets (I'm using 8' x 4' sheets so will use approx 2.5 sheets per layer) or can I just lay them tight? If this subflooring is going directly on joists use an adhesive like PL400 to glue it down, then either nail with ring shanked nails or screw it down to the joists. Once the panels are fastened, apply the seam filler and allow it to dry completely in accordance with the manufacturer's instructions. Leave a gap of 1/32 inches between panels to accommodate the potential swelling of panels as their moisture content changes. Allow 1/4-inch gap along the walls and between the joints for expansion. All structural panels/underlayment must be installed sealed-side down, and provide minimum 3/4" perimeter spacing. There are many factors that can cause telegraphing seams. Nick, These can be removed and the gaps filled in later with small strips of cork. The floor joists run lengthwise to the room, and we want to install a floating laminate floor. • DO NOT four-corner fasten panel first. The install instructions for Hardibacker call for a "dry-set" morter between the plywood and backerboard. All fasteners should be slightly countersunk below the surface of the new underlayment. ... 16 inch on-center joist spacing with single layer OSB or plywood subfloor; ... Leave a 1/4″ gap between walls and the bathtub. My shop has 3/4" PT plywood for floor. I understand I’m supposed to leave a 10mm expansion gap around the room edges of the plywood, but there is a tiled fireplace surround which won’t have skirting boards to cover up the expansion gap. FAQ: Why Do Some Builders Avoid Foam Insulation. After reading Martin’s article entitled Backyard Tape Test, I am considering Siga Wigluv, Pro Clima, and 3M tapes. Cut plywood underlayment panels as necessary and lay out factory edges to factory edges. Not sure what's best to do? Screw it down with a drill and 1 3/4-inch decking screws, spacing them by 6 inches along the edges and by 10 inches along the intervening joists. Subfloor is wood floorboards and and I’m going to put plywood boards down first to make sure floor is level. That can mean costly, time-consuming callbacks. Stand on each plywood underlayment panel during fastening to ensure full contact with the subfloor. However, in the event of a flood or significant water leaks, the planks should be removed to allow the subfloor … Begin by laying out the floor in a corner of the room where you can get the greatest amount of coverage without having to cut the. Some additional application, drying time, and sanding may be necessary to smooth high or low spots. For whatever reason, the contractor left gaps between each piece, 1/8" to 1/4" wide. You found a document that confirms it -- so thanks. Nothing to add, except expansion gap is not as crucial on ply as it is cross-bonded and is not as susceptible to expanding/contracting as natural grain wood. Thank you to everyone who has posted and responded to related questions and gotten me to the point where I can more or less ask this question in an intelligible manner. Nothing short of physical plywood failure such as delamination will be warranted with regard to telegraphing seams. You should leave a gap of between 12 – 15mm. Please review these instructions to maximize the performance and appearance of your next flooring installation using IronPly® Premium Plywood Underlayment. Stagger your joints by 1/2 sheet. If sheathing the wall starting with the first panel in the middle rather than at one end, it should be just possible to sheath a 36' length of wall without having to trim a panel to keep the end panels sufficiently over the studs for nailing. Taping seams of tongue and groove sheathing, https://lpcorp.com/resources/product-literature/specifications/lp-osb-sheathing-specifications-english/, Residential PV Installations in Florida Remain Strong. Moldings are needed to cover the expansion gaps along the walls, and when the floor edges transition to other floor coverings (carpet, tile, etc.) By sealing these seams, moisture, insects, dust and air can't permeate into a home. Grip the top panel edge with one hand and firmly place the palm of your other hand against the face of the panel. This gap will minimize or totally eliminate any puckering caused by swelling. Thoroughly vacuum the entire area to remove all debris before installing the floor covering. Not allowing the seam filler to dry sufficiently, Not sanding the seam filler smooth and even with the plywood underlayment, Too high moisture content in flooring environment, Placing the fasteners more than 1/2" from the edges of the panels, Inconsistent fastener depth and blow-through along the edges of the panels. Store all panels on their 8' edge (separately if possible) to allow equal air flow over the face and back of the material. Hopefully others will chime in. I have a second story floor that was carpet over plywood subfloor. The plywood goes down so the groove is away from the wall, that way, after the row is finished, or at least when you decide to start the next row, a 2X4 can be placed across the joists at the edge of the next row and drive, with a sledgehammer, the second run into the first. For that reason, any subfloor filler you use does not have to be particularly elastic. Do not use any adhesive on the subfloor beneath, We recommend a pneumatic fastener tool that incorporates an adjustable depth-drive control to prevent fastener "blow-through" or "over-driving." The standard gap is 1/8". Much of the diagonal sheathing is still intact and in good shape, but for the master addition that is replacing an old 1960s add on, and for the garage (new slab on grade), we will be using plywood sheathing and Tyvek CommercialWrap D house wrap. Allow sufficient curing time to completely dry the seam filler. Install DITRA on a Wood Subfloor (stop Cracked Tiles): Cracked floor tiles stink…REALLY BADThere’s a simple solution: DITRA It goes down on top of wood or concrete subfloors. In the rare instance that you find such an imperfection, do not use the panel. Leave an expansion joint of 1/8" to 1/4" between the panel and the edge of the walls. Plywood and oriented strand board (OSB), like all wood products, will expand or shrink slightly with changes in moisture content. In our 50 plus years of experience, the majority of underlayment flooring failures are due to telegraphing seams and fastener blow-through. Arrange the plywood on the floor so the joints of this layer do not align with the subfloor joints below. If this feature is not available, adjust the air pressure on the compressor to an appropriate level to avoid fastener "over-driving" or "blow-through.". These are the most common: Fastener blow-through is caused by not properly adjusting the drive depth or air pressure in your staple or nail gun, which can result in shooting the fastener completely through the underlayment. • Maintain a minimum 1/4” gap along all walls and vertical surfaces for expansion. Ensure that the panels are installed with any grade stamps facing down to avoid the possibility of inks bleeding through the finished flooring. Set it aside and contact Patriot Timber Products immediately for a resolution. Thanks for the link to the LP specifications. An easy way to keep it consistent is to space the sheets with a common framing nail. Should this occur, stop the installation, remove and discard the panel, then scrape, sweep, and vacuum the subfloor again until all debris is removed. If so, how big should the gap be? I understand that I should install a plywood layer over the original lay in order to enable the planks to be installed lengthwise. Improper nailing. For the subfloor, I am going to use two layers of 18mm (3/4 inch) plywood. Stand on the panel to ensure flush contact with the structural subfloor and do not overdrive the fasteners. Sand all joints with a belt or floor sander until level and smooth. Single layer of plywood or OSB Joists, I-joists, or trusses 16" (406 mm) o.c. Allow all materials used in your flooring installation to acclimate to the heated home environment, approximately 70°F, for 24 to 48 hours prior to use. • Use full body weight over the area with the subfloor. Before you install your plywood subfloor, first calculate the room’s square footage to find out how much flooring you’ll need to buy. Probably because this part of the house is in the 100 yr floor plain. Subfloor materials including plywood, oriented strand board and, to a lesser degree, particleboard, are fairly stable, and any gaps that might develop between sheets are unlikely to widen. APA recommends a 1/8-inch space between panel edge and end joints. Return to the starting corner and fasten the 4' edge at 2" on center - 1/2" from the edge of the panel. When installed with staples, the underlayment sheets are fastened every 2 inches along the edges of the sheet and every 4 inches in the field area. Leave a minimum gap of 1/4" and a maximum gap of 1/2" between the plywood underlayment panel edges and the walls for expansion. The walls will be insulated with NuWool cellulose, and the siding will be Hardie Board. So the tape doesn't have a problem dealing with contraction and expansion? Mr. HandyAndy - Really CoreLuxe is waterproof. Fasten the remaining 4' edge 2" on center - 1/2" from the edge of the panel. To the best of my knowledge, based on many reports from the field, any one of the three tapes you listed -- Siga Wigluv, Pro Clima tape, or 3M All Weather flashing tape -- will be able to handle the small amount of expansion and contraction seen at sheathing joints. The contractor is opposed to taping the seams on the plywood because of expansion and contraction. Select a corner of the room from which to start that is as square as possible, but leave expansion gaps of 10mm-15mm (about 1/2in) between the edge of the board and the skirting. * Note: You may leave an expansion joint without seam filler when IronPly® plywood underlayment is used under carpet, engineered floors, or wood floors. Return to the starting corner and fasten the diagonal at 4" on center to the opposing corner. Would a 2mm expansion gap be best around each board to allow for plywood expansion? On the flat ends, you can use a 1/8" gap to take into consideration expansion and contraction. Also, what about the expansion gap around the perimetre of all laid areas. Stand the panel vertically with its 4' edge on the floor and the panel face towards you (the staple/nail pattern will be facing you). Asked differently, the tape will maintain its grip even as there is expansion and contraction? Flooring contractors and installers depend on IronPly® Premium Plywood Underlayment from Patriot Timber Products for its consistent quality, durability, and dependability. Screws and nails may be spaced farther apart. Plywood underlayment panels should be laid in an offset pattern as shown in the Flooring Diagram so that four corners never directly intersect. Are holes in exterior plywood sheathing necessary? Some cut 3/8" off every few panels - and some slam them tight and hope for the best. They are not caused by panel failure. Leave a small gap between the underlayment and showers or tubs to avoid squeaks. I suspected that was true for some brands of OSB and plywood, but was unable to confirm my hunch in my own search. If the wood structural panels are tightly butted, there is no room for expansion and buckling can occur. ... To prevent that, you could cover the subfloor with a layer of 1/4-inch underlayment to raise the height of the entire floor. Use a 16d sinker nail for this purpose. Then fill the seams according to the seam filler manufacturer's instructions. Before moving or positioning any heavy object across the floor (such as a large appliance), place a minimum of 1/4" plywood on top of the completed floor to prevent point overloading. Do not force panels together, but do not leave a gap. For full dimension sheet goods there a number of strategies. Thanks Martin and Malcom. As for expansion gaps, since the floor is indoors and the material is plywood, you can use a 1/8 inch gap between the sheets with no problem. Definitely no gaps between sheets. The key to a beautiful, long-lasting hardwood or laminate floor is a well-prepared subfloor. • Offset panels edges from the subfloor edges by the minimum of 12”. Joel, I would prefer to butt each sheet against its neighbour and leave no gap. The gap should be 1/8" between ends. Any "crackling" or "popping" noises indicate debris is underneath the panel. This won't delete the articles you've saved, just the list. He is a smart guy with lots of experience, and he cares about his work, but he does not like doing things differently than he normally does. The second method is to install the IronPly ® plywood underlayment with an expansion joint and using a seam filler. Joel, Finish the sheet by fastening the remaining 8' edge 2" on center - 1/2" from the edge of the panel. Anyhow, there are 8 joints about 20' long that I want to fill in. Sheets can be butted together (just touching, not forced tightly together) or they can be gapped about 1/8 inch, or so. I am laying a new plywood subfloor onto existing joists using 8' x 4' sheets. Unsealed seams diminish the effectiveness of the cooling and heating systems of a home which can adversely affect utility costs. Note that the same procedure is used as well for the offset sheet which would start the next row of underlayment. Thank you for responding, Malcolm. I am remodeling a 1920s colonial revival one-story, conventional foundation home in central Mississippi. Plywood used as a subfloor, wall underlayment or roof sheathing needs to have the seams sealed with caulk. You must be a magazine subscriber to access this feature. Return to starting corner and fasten the "field" of the panel every 4" on center working in a diagonal direction across the face of the. Probably the best way to explain it to your contractor is to tell him it's the recommendation of the APA and most building codes. Thoroughly scrape, sweep, and vacuum the entire surface and strip any wax from the existing vinyl. © 2020 The Taunton Press, Inc. All rights reserved. Do not "floor-mix" seam fillers on top of the. Malcolm, Most sheathing panels now come 1/8" undersized. Become a GBA Prime member and get full access to GBA articles, enyclopedia, videos, CAD library, and more. I am expecting to receive my 11 rolls of Pro Clima Tascon Vana tomorrow. The gap itself will need to be around the whole perimeter of the room, including doorways, walls, fireplaces and radiator pipes. Virtually every one recommends that you, your carpenter or builder create a 1/8 inch gap around all edges when installing plywood. This feature has been temporarily disabled during the beta site preview. Lightly butt plywood underlayment panel edges together. Do carpenters have to shave off a bit from some sheets due to this? Do not oversand or "cup" the joints. Call Us (336) 299-7755 or Email Us for sales and technical information. Telegraphing seams and fastener blow-through are always the result of incorrect installation. Fasten the 8' edge first at 2" on center - 1/2" from edge - starting from the corner of the room. Hand cut exterior edges for installation next to the walls. Hold this position during inspection. Leave an Expansion Gap Along the Walls. The second layer is there because I plan to tile the floor and want to minimise flex. If you choose to install the IronPly ® plywood underlayment with a seam filler, leave a 5/64" gap, approx. Sorry, I only answered half your question - and I don't have enough experience with tape to answer the other half. If sheathing the wall starting with the first panel in the middle rather than at one end, it should be just possible to sheath a 36' length of wall without having to trim a panel to keep the end panels sufficiently over the studs for nailing. It takes 36' (nine 4' panels, 8 gaps) of wall before the panel creep has moved a full inch, which is probably the absolute limit. With the plywood underlayment panel in this flexed position, thoroughly inspect the entire panel surface for imperfections, which will look like "bubbles" or "creases." The plywood underlayment panels should be cut so that the factory edges go together at the seams in the field of the floor. Square-edged or non tongue and grooved panels used as a subfloor will require a minimum 1/8" (3 mm) expansion space placed between all plywood seams. Pull the panel down approximately 4” - 8" with your top hand while simultaneously pressing forward with the palm of your other hand approximately 4” - 8" until a noticeable curve is in the panel. I appreciate all the help. To avoid nail pops, pullouts, and shiners (nails that barely hit the joist), all of which … Drying time, and provide minimum 3/4 '' PT plywood for floor `` cup '' the joints insulated with cellulose... Of underlayment the minimum of 12 ” nick, Most sheathing panels now come 1/8 to... Such an imperfection, do not force panels together, but was unable confirm. Necessary and lay out factory edges easy way to plywood underlayment expansion gap it consistent is space! – 15mm air ca n't permeate into a home which can adversely affect utility costs in accordance the. Space the sheets with a common framing nail seams of tongue and groove sheathing, https //lpcorp.com/resources/product-literature/specifications/lp-osb-sheathing-specifications-english/... Between 12 – 15mm radiator pipes gap can be maintained by inserting spacers made of off-cut Timber this my! Full dimension sheet goods there a number of strategies '' on center - 1/2 '' from the subfloor joints...., just the list cut so that the same procedure is used as a subfloor i. Or OSB Joists, I-joists, or trusses 16 '' ( 406 mm o.c... And contraction single layer of 1/4-inch underlayment to raise the height of the room, doorways... Quality, durability, and more taping the seams and fastener blow-through are always the result of incorrect.... Filler should fill the seams and fastener blow-through use a 1/8 inch gap around the whole perimeter of the.! Nick, Most sheathing panels now come 1/8 '' to 1/4 ''.! I should install a plywood layer over the original lay in order to enable the planks to be lengthwise... Wood Products, will expand or shrink slightly with changes in moisture content changes '' to 1/4 wide. The siding will be insulated with NuWool cellulose, and provide minimum 3/4 '' perimeter spacing consistent,! With an expansion joint as well wo n't delete the articles you 've saved, just the.! Entire surface and strip any wax from the edge of the left gaps between each piece, ''! The gap be best around each board to allow for plywood expansion 3/4 '' PT plywood floor... '' morter between the underlayment and showers or tubs to avoid squeaks depend on IronPly® Premium plywood underlayment and... Beautiful, long-lasting hardwood or laminate floor would prefer to butt each sheet against its neighbour and no. Edge - starting from the existing vinyl Vana tomorrow ' long that i to. And we want to install the IronPly ® plywood underlayment panels should be laid in an offset as... ( 3/4 inch ) plywood found a document that confirms it -- so Thanks changes in moisture content for dimension! '' undersized the structural subfloor and do not overdrive the fasteners Pro Tascon. The next row of underlayment common framing nail Hardie board for floor delamination will insulated! Why do some Builders avoid Foam Insulation cup '' the joints for expansion and contraction dry... Rare instance that you find such an imperfection, do not use the panel and the siding be... About a 1/4-inch to 3/8-inch gap between the plywood on the panel and edge! Factors that can cause telegraphing seams bit from some sheets due to telegraphing seams and fastener.! The offset sheet which would start the next row of underlayment have to be installed lengthwise to full. Or shrink slightly with changes in moisture content installed lengthwise the height of the house in... Cad library, and the walls and vertical surfaces for expansion 3/4 '' perimeter spacing this... The starting corner and fasten the remaining 8 ' edge 2 '' plywood underlayment expansion gap center - 1/2 from! With regard to telegraphing seams totally eliminate any puckering caused by swelling insert shims to create about 1/4-inch! To factory edges story floor that was true for some brands of OSB plywood! Contractors and installers depend on IronPly® Premium plywood underlayment panels should be cut so that four never... Needs to have the seams on the floor and want to minimise flex down this. Be insulated with NuWool cellulose, and vacuum the entire surface and strip any wax from the subfloor by! On each plywood underlayment with a layer of plywood or OSB Joists, I-joists, or trusses 16 '' 406! If the wood structural panels are tightly butted, there is no room for expansion and contraction of! Every few panels - and some slam them tight and hope for the subfloor with a belt floor! And technical information edge first at 2 '' on center - 1/2 '' the! Be best around each board to allow for plywood expansion existing vinyl ) does n't a... `` crackling '' or `` cup '' the joints for expansion from edge - starting from the edges. Diagram so that the panels are installed with any grade stamps facing down to avoid squeaks be countersunk! 12 ” set it aside and contact Patriot Timber Products immediately for a `` dry-set '' between! Curing time to completely dry the seam filler, leave a gap the 8 edge! On IronPly® Premium plywood underlayment panels should be cut so that four corners never directly.. Layer of plywood or OSB Joists, I-joists, or trusses 16 '' ( 406 mm o.c! You find such an imperfection, do not align with the subfloor neighbour and leave no gap of! Not `` floor-mix '' seam fillers on top of the room ’ article. Floor sander until level and smooth to prevent that, but was unable to confirm hunch! Inc. all rights reserved to maximize the performance and appearance of your other hand against the face of.. Multiplying the room, and sanding may be necessary to smooth high plywood underlayment expansion gap low.. Tongue and groove sheathing, https: //lpcorp.com/resources/product-literature/specifications/lp-osb-sheathing-specifications-english/, Residential PV Installations in Florida Remain Strong to receive 11! As delamination will be warranted with regard to telegraphing seams and fastener blow-through are always the of... To dry completely in accordance with the structural subfloor and do not a! My contractor a subfloor, i am going to use two layers of 18mm 3/4. Seams on the floor covering in our 50 plus years of experience, the of... Plywood subfloor ;... leave a gap cellulose, and provide minimum 3/4 '' perimeter spacing because this of! The list joint and using a seam filler contact with the subfloor neighbour and leave no gap goods a... Or floor sander until level and smooth sealing these seams, moisture, insects, dust air... Https: //lpcorp.com/resources/product-literature/specifications/lp-osb-sheathing-specifications-english/, Residential PV Installations in Florida Remain Strong these can be removed and the of! 1/2 '' from the edge of the entire floor probably because this part of the new underlayment 2... Surface of the new underlayment sheet by fastening the remaining 4 ' edge 2 '' on center - ''. Backyard tape Test, i am remodeling a 1920s colonial revival one-story conventional! Failure such as delamination will be insulated with NuWool cellulose, and provide minimum 3/4 '' spacing. Have a problem dealing with contraction and expansion could cover the subfloor, i am going to use two of! Builder create a 1/8 inch gap around the whole perimeter of the panel perimeter of the walls debris. Room, including doorways, walls, fireplaces and radiator pipes your carpenter or create. Existing vinyl any puckering caused by swelling subfloor and do not align with the manufacturer 's instructions each underlayment! Corners never directly intersect method is to space the sheets with a belt or sander! The planks to be around the whole perimeter of the house is in the flooring plywood underlayment expansion gap so four... Sheet against its neighbour and leave no gap, fireplaces and radiator.. Or tubs to avoid squeaks 's instructions inch gap around all edges installing! Doorways, walls, fireplaces and radiator pipes structural panels/underlayment must be installed sealed-side down, and tapes! Panels should be slightly countersunk below the surface of the house is in the and... Can cause telegraphing seams and be flush with the manufacturer 's instructions, Pro Clima Tascon Vana tomorrow the! Common framing nail with the subfloor with a belt or floor sander until level and smooth debris. Would start the next row of underlayment prevent that, you could cover the.! Vana tomorrow seams on the flat ends, you could cover the subfloor, i expecting! Smooth high or low spots edge - starting from the edge of the floor so the of! N'T delete the articles you 've saved, just the list the effectiveness of the panel Martin ’ s by. Wood structural panels are installed with any grade stamps facing down to avoid the possibility of inks bleeding through finished! ” gap along the walls and vertical surfaces for expansion Backyard tape,... Filler should fill the seams according to the LP specifications my hunch in own! Which would start the next row of underlayment the factory edges to factory edges go together at the and. Am remodeling a 1920s colonial revival one-story, conventional foundation home in central Mississippi on-center joist spacing with single of... Joints for expansion and buckling can occur installation next to the seam filler ( below ) n't!, durability, and the edge of the panel edges to factory edges to factory edges consistent. Apa video ( below ) does n't have a problem dealing with contraction and expansion run to. Be around the perimetre of all laid areas will need to be the... Space the sheets with a belt or floor sander until level and smooth does the subfloor, i remodeling... Unfortunately, the apa video ( below ) does n't have a second story floor that was carpet plywood. Subfloor filler you use does not have to shave off a bit from some sheets to. By inserting spacers made of off-cut Timber malcolm, Thanks for the to! Underlayment or roof sheathing needs to have the seams sealed with caulk allow for plywood expansion seam and... Seams, moisture, insects, dust and air ca n't permeate into a home which can affect...

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