Do you know? When plywood gets wet, it swells evenly across the plywood sheet, and then when it dries out it goes back to the normal sizing. When planning to redo your roof or repair some damages, you might come across different grades and types of wood, such as OSB and CDX and start wondering what those abbreviations mean. Overtime, plywood has shown experience to dry much quicker than OSB. This Spring, I was busy, busy building a big playhouse for my kids. Step 1: Use seam tape on plywood joints and flashing where deck meets the house (seam tape can be seen upon finished system.) Generally, plywood roof decking that has gotten wet and had the shingles applied over it, if allowed to dry out, will not be seriously damaged by wood rot fungus organisms. This will ensure that the strength of the plywood is enough to bridge spots on the roof where the old plywood was weakened to the point that it would sag under the load on the roof. I am using a 7/16" OSB Sheathing that I got from Lowe's. Plywood for roof sheathing must be suitable for exterior use, graded “Exterior” or “Exposure 1.” … These layers help give the material its strength, and ensure that it remains stable enough to be used for many different purposes, from creating a roof deck to building cabinets. Especially in relation to OSB or Plywood use for Roofs, Walls & Floors. It’s here that plywood has the … The biggest difference between the two panels is how they react when exposed to large amounts of moisture over extended time periods. This is why plywood is considered as the better option for roofing. Lay felt paper onto the roof, overlapping the existing paper to get good coverage. Staple it to the roof decking or nail it with plastic-capped roofing nails. But, the playhouse has a recessed upper deck on one half of the roof. Plywood for floor underlayment can’t be used inter-changeably for roof sheathing. If you are handy, or have a handy friend, and there is only one defect, can likely either replace a broken shingle or repair protruding nail head(s) and seal them up. However, due to its water repellent properties, it acts more as a shield than a sponge. I used floor underlayment for roof sheathing simply because I had some… and it seems to delaminate when it gets wet! Pitch a fit and either get the roof in the dry or get those shingles on. How long is too long for felt paper to be left on the roof with no shingles? When Roof Felt Gets Wet. DEAR TIM: My builder insists that 5/8" OSB plywood is fine for the roof. Installing shingles over wet decking also will void any warranty you might have from the shingle manufacturer. A: It is never a good idea to install a roof over wet plywood or any type of roof sheathing. Another reason for wet and rotted sheathing in the lower 1/3 of the roof is ice dams. We're building a sunroom addition, nuts to do this in winter, especially this winter in the Atlanta area, but so it is. Do not use caulking, roof tar or asphalt mixes to cover flashing materials. The roof itself is not bad. A: It is never a good idea to install a roof over wet plywood or any type of roof sheathing. Is there a way to clean the plywood and re-baffle? If you have either an old roof or leaks scattered about, you may need a new roof. Oy. Shingles will not stick properly to the wet roof decking like plywood; Keeping moisture trapped in roof decking causes the roof to swell up or buckle; Trapped humidity can cause mold and mildew growth, which deteriorates the condition of your property; However, if any roofer has started working on a residential roof’s installation process, and it suddenly starts to rain, they should … November 16, 2020 at 11:17 am. I designed it to look like a mini version of our barn. The plywood is NOT rotted. Wondering if I need to wait until the plywood is totally sun dried. Overall, plywood is a little bit better for roofing. Now you're ready to replace the shingles … Plywood on the other hand, is made with thin sheets of wood that have been cut from a spinning log, then glued together with the grain laid out in alternating … When used as roof sheathing, this tendency to hold moisture means it will degrade faster than plywood when exposed to chronic leaks. Contemporary plywood was first patented in the mid-1800s, and production began in earnest in Portland, Oregon, in 1905. The roof is ready for the tar paper but we had some rain this morning. ft. Elasto-Barrier® and embed Contouring Roof Fabric™ into wet coating. Baltic Birch Plywood: This is a high-quality plywood … This post is all about how to waterproof a plywood deck, roof or balcony with Liquid Rubber Deck Coating. Softwood plywood is typically used as structural plywood (roof decking, sheathing, flooring). Today, builders can choose from several types of exterior plywood. We could, once the roof is complete and the building is closed in, get a de-humidifier in there and really cook the place dry before installing the flooring, but what about all those plywood bubbles? AAJW Lazenby : 5/29/01 9:25 PM: The biggest concern with exposed building paper (felt) on the roof is the customer/home owner. Or does all of it have to be ripped off. Lastly it would be … When the roofing material dries quicker, it can be used to make sure that the roof will stay firm for a longer time. Swollen edges have been … It actually didn't bring the massive amounts of rain it was predicted to. Exterior plywood came on the scene in 1934 with the development of a waterproof adhesive. Step 2: Apply 2 gallons per 100 sq. Plywood’s Superior Wet Performance. Roll excess Elasto-Barrier® over top of the Contouring Roof Fabric™ and allow to dry. Please advise…Thank you. OSB takes longer than plywood to get saturated, but also takes much longer to dry out. Step 3: Finish … In this case, plywood has the edge. Roof felt serves as a protective layer between the OSB and CDX do not only look different, but they have unique … Trapped water will boil when the sun heats the roof and the shingles will then have small pits where the steam finally escapes. Do you think that we will have any problems with our OSB sheathing roof? I was planning on putting plywood over the rafters and crossing the rafters with a 2-by-4 every 16 inches as strapping to secure the metal roof. A 4’ x 8’ sheet of 1/2-inch APA Standard Plywood would weigh 48 lbs. Address any edges that are of concern to make the roof level and flat before installing the finished roof material but this should not be done until the panels have had time to dry. How to Waterproof A Plywood Deck, Roof or Balcony. You also should consider the design parameters of the roof to ensure that the extra weight of the added plywood is well within the static load capability of the roof support structure. Apply another coat of Elasto-Barrier®. The felt can get wet. In This video I show how to replace rotten plywood on your roof without breaking your back! Installing shingles over wet decking also will void any warranty you might have from the shingle manufacturer. And rain is forecast for tomorrow and the next day so I would like to try to get this rood completed. Is one better for roofing than the other? The shingles are in place to protect the felt. … Once plywood has become wet, you must encourage the water that has soaked into the wood fibers to evaporate to make it dry again. The APA Standard weights are not the weights of actual products and tend to be somewhat heavier than the weights of any real softwood plywood you will find. With the exception of projects in very arid regions like the Southwest, sheathing and flooring panels are routinely covered with rain, snow, and ice during construction delays. Because Plywood dries out relatively quickly, the swelling is usually not enough to affect roof finishes. I'm in southern NJ, right across the river from philly and we're the middle of hurricane sandy right now. When OSB does get wet it also tends to swell along the edges, and those edges stay swollen even after the material has dried out. Plywood is made up of varying layers or plies of wood, usually with a hardwood or veneer top surface. When he begins to loose faith, there is hell to pay following. OSB Plywood Outdoor | Roofing text: Tim Carter. When used as a roof sheathing, this tendency to hold moisture means it can degrade faster than plywood when exposed to chronic leaks. Weather proof is more difficult because it requires the plywood to get wet and dry intervally in order to simulate the raining weather. Some roof problems could stem from panels installed over wet decking. Once plywood has become wet, you must encourage the water that has soaked into the wood fibers to evaporate to make it dry again. Building paper flapping in the … Will wet plywood dry out? Cover the seams between the old and new decking with bitumen tape. Once you repair the hole in the roof plywood, you need to seal up the seams and recover the roof. From what I’ve read online, it … James Katzin, Emlenton, PA Some bays have small amount of mold some dont. The plywood around the chimney was wet to the touch, … The wet and rotted wood in this location could be the result of gutters which are dirty and often full of water. Stack loose sheets of wet plywood in a … Not only will it swell, but the wood chips will also break away. I'm doing a lot of the work myself, help from a metal roofer with other skills. This means WBP Plywood can not only pass the hot water boiling test, but also can get wet and dry, wet and dry, without delamination. wet. The felt is actually what keeps your roof dry! The drying out period is relatively short, which means that it doesn’t affect the roofing. This self-adhered membrane is highly durable and comes in a 225 sq. William. The OSB board got wet after one significant rainstorm before the shingles were able to be put on. The felt collects and then repels the water, allowing the roof to breathe. If that is the case, than the extent of the rot should be limited. Should I use CDX or OSB for roofing plywood? A 4 x 8 sheet of plywood covers about 32 square feet of roof area—and the average roof … While the glue is waterproof, the wooden layers aren’t, and they can swell or deform when exposed to moisture. Of course, you don’t want either of these decking materials to become saturated. The Minimum Plywood for Roofing. The airflow was obstructed from the soffit vents to the ridge vent by too much insulation and no baffling. What are the differences? Next week it should be clear, and we will finish the install. Most roofs' rafters are set 2 feet apart and the plywood decking should be a minimum of 7/16 of an inch thick. I went into the attic to check it out an hour ago and noticed that a very small, and intermittent drip of water was coming down our plumbing vent. OSB vs Plywood Screw Holding Even though the wood is porous, it is more natural and it can dry quickly. OSB takes longer to get wet than plywood but also takes longer to dry out. Roofs are framed with rafters or trusses, which are rafters joined by internal braces so they install as a single component. WBP is short for Weather and Boil Proof, not short for Water Boil Proof. Concrete is in most basements as no floor joist is present. Plywood is often used in roofing because it performs well when exposed to moisture over long periods of time. Your price could vary depending on how much the roofing company charges for labor, but generally you can expect to spend between $70 to $100 for each sheet of plywood. And in case you’re wondering, yes, the I-joists holding up the subfloor also got wet (primarily the plywood caps, not so much the OSB ribs). When OSB gets wet, it will swell over time. Glenn says. The result being that water wicks up and onto the plywood. Also, with that amount of rain, plywood and OSB may have some swelling at the edges and a thorough inspection of the panels should be done after the panels have completely dried. We didn’t get the roof on yet, and even though we tried to rig up some protection, we had rain and then a few leaks. Should I worry about the wet roof? 1. OSB is made of small and fairly rectangular-shaped wood chips from small resinous trees, which are bonded into a panel form with wax and synthetic resin. It can withstand very harsh … But like all wood, each layer of the plywood can absorb moisture, whether from direct contact or through … Bag up the wet insulation and get it out, then put down a tarp until the leak is repaired. My roof build up has plywood, 3” of polyiso, and a second plywood deck.