Will plywood sheathing that’s been wet smell bad? If so, will it ever stop smelling?
The house we moved into 6 months ago has an addition (built around 1989) with a bad odor. To me it smells like plastic or glue or some other chemical. To my wife it smells like wood.
As a side-effect of 1st floor window and door replacement we’re replacing all of the cedar clapboards on the addition. The contractor replacing the doors said that there was no tar paper or tyvek behind the clapboards so he couldn’t properly weatherproof the new windows and doors. We decided to remove the clapboards, install tyvek, properly flash everything and put up new cedar claps. Did the 1st floor only.
During heavy spring rain I noticed brown stains that were obviously from water dripping out from under some of the clapboards. Also saw several large, water-filled blisters in the paint. I guessed that the 2nd floor windows must also have inadequate flashing so called the contractor back to do the same job on the second floor.
He has the wall stripped and found no rotted sheathing but red rosin paper, lots of moisture, and ants behind the clapboards. He put up the tyvek and left it for the Memorial Day weekend. It was warm and dry here most of the weekend.
It rained a little Monday night & Tuesday, then the sun came back and the odor came out with a vengeance.
What I’m wondering is if this smell could be coming from the plywood sheathing and if so, should it be replaced? Replacing the clapbaords was bad enough but demo-ing and replacing all the sheathing seems insane. But if I can’t get rid of this smell I’m going to have to move.
Maybe a better question is: How can I figure out where this smell comes from?
Replies
Tough situation. Moisture can be a tricky thing. You need to dry it out and get rid of the ants for sure.
Finding the source of the smell is one thing. Finding the source of the water/moisture is another. Won't do any good to dry it out if, e.g. you have a leak in a roof that runs down under the sheathing to the wall top. (don't discount this unless you know it doesn't exist for a fact ... I've seen some strange things in my day). Always good to do a reality check to see if murphy is out there.
No tyvek or felt is ... in my opinion a bad idea. I'm not an expert here, though. But decades of use of a material by hundreds of thousands of builders ... usually means that it has a purpose ... and I know it is related to water/moisture.
If I get eye rollers jumping in here to set me straight and explain things ... I've done my little part here ... to your benefit. Good luck
We had the whole roof stripped and redone with 40 year architectural shingles just before we moved in (6 months ago). Previously, there was a leak near one of the walls in question but I'm pretty confident that it is fixed now. The roofers seem to have done an excellent job in general.But one thing that bothers me about the roof is that there is no overhang on the gable ends, except about 1" over the fascia board. There is (now) an aluminum drip edge. I think that wall may get a lot of water over it when the wind blows from the west (common) sweeps rainwater off the roof so it runs down the wall. But it seems that if it's built right it should shed that water OK. (Murphy notwithstanding.) I've been working on the hypothesis that it wasn't shedding water OK because the windows and doors were not properly flashed.
If that west wall is your problem and you have nothing under the siding, my guess is ... that is your problem. While maybe a PITA to strip the wall of siding, it may be your best approach. Lots of talk in recent years about various const techniques to apply siding and have a drain/air layer behind it ... I'm sure some of the guys know some of the ins/outs of those options. Used a lot w/ wind driven rain (e.g. hurricanes), I think. I did eaveless gables ... once. While an eave is more work, it has a purpose, so I would not recommend them as they can be sources of problems. Does your siding butt up to the gable end trim? If so ... can be the source of water entry ... particularly in winter w/ ice, etc.
I'm not there now but I'm pretty sure the trim on the gable end overlaps the siding. BTW, Thanks very much for your help on this. I've done a lot to get control of this odor problem. I do think the moisture problem is a serious one, whether it accounts for the odor or not so I'm spending the green to get the tyvek, window flashing and siding done right. But I sure hope it fixes the odor too.
I'm going to throw out some ideas, may not solve the problem but may eliminate some causes.
Is the smell just in the addition or the whole house?
Is it worse outside or in?
1st floor or 2nd?
Does the house/addition have a vapor barrier? Pull some switch plates and check.
Does the ceiling have a vapor barrier?
Does the house and the addition have a shared attic? If no, can you access the addition attic?
Climb up into the attic(s)... is the odor any stronger? Is the insulation wet?...are there any black (mold) stains on the rafters/trusses?...is there enough ventilation...are the soffits breathing or are they plugged?...Do you have roof vents? are they providing enough air flow?
Do you have a bathroom fan? does it vent outside or does it dump into the attic?... where the addition meets the existing house, is it a solid connection or has it opened up due to different rates of settling?
Up on the roof...is the plumbing stack properly flashed? any other penetrations like chimneys or skylights?
If there was a leak in the roof before you moved in ,it would have soaked the insulation and the framing, providing a growth spot for mold/fungus.
If the water is entering the attic via the gable end it would explain the smell caused by rotting wood because the insulation is acting as a giant sponge. Excess water then hits the vapor barrier on the ceiling and is expelled back though the siding.
tell us what you find
toolman65
> Is the smell just in the addition or the whole house?Just in the addition. > Is it worse outside or in?Worse inside, for sure. > 1st floor or 2nd?Strong in both. I taped plastic over the bottom of the stairway for a while and it did seem to diminish in the downstairs but it didn't go away.> Does the house/addition have a vapor barrier? Pull some switch
> plates and check.There is a poly vapor barrier in the walls. > Does the ceiling have a vapor barrier?Not sure about the 1st floor ceiling but I suppose that doesn't matter much. I'm pretty sure the 2nd floor ceiling has a vapor barrier but I will check if I can. Come to think of it, I think I've seen the edges of it in the attic crawl spaces (behind the knee walls upstairs). I can't tell but I hope that the VB in the walls is somehow sealed to the VB in the ceiling at the joint where they meet.> Does the house and the addition have a shared attic? If no, can you
> access the addition attic?No. Attics are completely separate. I can access only crawl spaces behind the knee walls in the addition. There's a small part at the peak that is inaccessible - maybe 5 feet wide.> Climb up into the attic(s)... is the odor any stronger? I have not found it to be stronger in the crawl spaces. If anything, I think it's less.> Is the insulation wet?...are there any black (mold) stains on the
> rafters/trusses?I haven't seen any wet insulation or signs of mold in the crawl spaces.> ...is there enough ventilation...are the soffits
> breathing or are they plugged?...Do you have roof vents? are they
> providing enough air flow?Ridge vents and (probably inadequate?) soffit vents. The soffit vents are about 4"x10" grills spaced about ... I'm working from memory ... maybe every other joist bay.> Do you have a bathroom fan? does it vent outside or does it dump
> into the attic?... 1 full bath and 1 half-bath in the addition, both with fans that vent outside.> where the addition meets the existing house, is
> it a solid connection or has it opened up due to different rates of
> settling?As far as I can see it's solid. The original house is 200 years old tho and the foundation is fieldstone. But it does seem to be well sealed off from the new addition foundation except for one opening at the top of the basement wall, about 1-1/2' x 1' where pipes pass through. The old foundation has 1 small leak in a corner which I think will be fixed when I replace the roof gutters and channel the downspout into a pipe I dug into the lawn that runs away into the bushes (about 12' away).The new foundation does leak tho. I need more gutters. In the spring I had 1/4" of water over 2/3 of the basement floor a few times when we had very heavy rains. (There's a sump pump but it's poorly installed. I'm going to have a drain cut around the perimeter of the basement floor to channel water into the sump.) But it's been dry for the last 2 months with a dehumidifier keeping the RH around 50%.> Up on the roof...is the plumbing stack properly flashed? any other
> penetrations like chimneys or skylights?There are 2 plumbing vents and a stainless steel chimney for the oil burner penetrating that roof. I have not seen any signs of leaks (but I can't see the underside of the roof around the plumbing vents). The roof is new and seems to have been well done. The chimney is new and had to be cut through both floors of the house and I still haven't finished the ceiling around it on the 2nd floor. So I guess I should get a flashlight and a step ladder and see if I can see anything up there through that hole.> If there was a leak in the roof before you moved in ,it would have
> soaked the insulation and the framing, providing a growth spot for
> mold/fungus.Ahhh... this is something I have to check. I guess I could cut out some drywall in the upstairs bedroom. Not looking forward to having another thing to fix though.If the insulation is wet, does it have to be removed or will it dry out eventually?I have a moisture meter (pin type, for measuring moisture content of lumber). Do you think I could get a good read on moisture in the walls with that? What sort of level would be alarming?> If the water is entering the attic via the gable end it would
> explain the smell caused by rotting wood because the insulation is
> acting as a giant sponge. Excess water then hits the vapor barrier
> on the ceiling and is expelled back though the siding.Man, that does sound likely. Ugh.
> tell us what you findDefinitely will. Many thanks.
Glad to help some other things to consider;are your gutters functional? does water actually flow down the spout?are they clean or full of crud? are they properly installed with the right amount of grading?If they aren't draining you may have alot of standing water...full of crud water. when it rains the gutters overflow, and this soup must go somewhere....perhaps the space between the fascia and the gutter rather than over the side... it then goes across the soffit and under your siding.are the addition and house gutters linked? where do the downspouts go?
are they tied into the septic system drain? Many houses of your vintage had cisterns...that were supplied by....the downspouts.perhaps when your cistern was removed, the downspouts were never re-jigged and have been dumping water around your foundation for years.the reason why the smell may be stronger in the addition is because old houses had no vapor barrier and can breathe much more than ..say...a new addition wrapped in plastic.also,standing water in a basement is a breeding ground for mold and other nasty stuff. even after the water has been pumped the residual moisture can still turn your place into a petrie dish. Pull as much stuff off the floor as you can. Check for any water stains( along the wall or inside the furnace) to determine how high the water got before you bought the house.Use a spray bottle filled with bleach and do along the edges and corners of the slab. See if smell reduces. Also check the floor drain for enough water to form a trap seal.Finally, the ugly one.how you deal with waste water now? septic bed? how old?how far from the addition?Given the age of the house...200 plus years....there have been several attempts to deal with the "offcuts" of human occupation;outhouses, garbage dumps, septic beds of old.where are they? where is this addition in relation to them?could it be that the addition, with its leaking foundation, shares a water table with an abandoned septic bed? Nuke the basement with bleach regardless. I have been in basements that have been flooded by a broken septic pipe....Biohazard!best of lucktoolman 65
Actually, we had the house painted before moving in and since the aluminum gutters were all banged up, improperly sloped and otherwise crummy, I had the painters remove them. I've yet to put up new ones. So while there is no chance of overflowing gutters washing down the walls, the roof runoff certainly does contribute to the water in the basement. But overflowing gutters were definitely a problem before we removed them so if the wall cavities are wet that may be the reason or part of the reason why.The old downspouts just dumped out onto the ground. (One of my summer projects is to dig a couple of small drywells and bury PVC pipes from downspouts to drywells or to downhill locations where they can drain to daylight.)I've given the basement walls and floor a good inspection and see no signs of crud. The smell in the house doesn't seem like a sewage smell. The furnace is new - wasn't there before we bought the house so I was able to see all of the walls clearly. It doesn't look like the water ever rose above 1/2" as far as I can tell. There is no floor drain (except for the hole cut in the slab for the sump pump).Interestingly, the basement doesn't smell. In fact the air down there is probably better than in the living room. I suppose that's another clue that points to moisture upstairs, possibly in the wall cavities.The current septic system is at the other end of the house and a good distance away from the addition - I'd say well over 100' away. It seems to be functioning well.
Some out of the box thoughts here. Might sound silly but....
Do you know if the previous owner had cats? They can make a place smell pretty bad. Especially if its carpeted and they urinate wherever they feel like it.
Any nooks or crannies where mice or a small rodent could get in and die? They also give off a pretty horrible smell as they decompose...espeically for how small they are.
Good points. I know the previous owner did have at least one cat and 2 or 3 dogs. Judging from the hole cut into the bottom of a beautiful 18th century door (grrrr....) between the master bedroom and master bath I'm guessing the that cat's litter box was in the master bath. That bathroom is not in the addition that has the odor. One of the things I've done in trying to eliminate this odor is to seal all the interior surfaces in the living room with shellac or shellac-based primer. I put clear shellac on the oak floor and built-in cabinets and BIN on all walls and ceiling. I used BIN on the interiors of the builtins. Hopefully that would help if it was a pet odor.I don't think it's a dead mouse because I've experienced that gift of nature before and this is not that same smell. Thanks for your thoughts tho!
several years ago a had some clients, young couple. Did a fair amount of work on their older 1950's bungalow. Basement had been renovated before they bought. mentioned to me once in passing if i could find the source of a dank smell coming from their basement freezer. so i check out the freezer itself; newer unit , no leaks, no stains on the rolled flooring. i'm stumped.
so i ask "did the freezer ever smell when it was at your old house?"reply; " oh no, that came with the house. They made it part of the sale, they were so generous""Have you moved it since you bought the house?""No,why would we?"so, just for fun, i move the freezer....and i discover that under the brand new lino....the floor was rotted.it all made sense now. the previous owners had a leaking freezer...may have leaked for years...they replace it with a new unit and put it exactly where the old one was....then they decide to renovate and replace the old stained lino....so they either do it themselves or hire the village idiot to pull the old flooring and lay fresh lino over the rot.Then they decide to sell...leaving the new freezer behind to cover up their stupidity. Don't ya just love old houses!anyway, glad to here the smell is reduced in your basement. now, could this smell be sewer gas? when the addition was built, did they tap into the existing sewer system? was the vent pipe run though the roof or left short in the attic? (seen it done)never did ask what type of insulation is in your attic. I assume fibreglas for the addition, but what about the old side?When someone throws a mattress out and it gets soaked by the rain, then cooked by the sun....is that the type of smell you mean?if it is , then we're back to soaked insulation.what type of ants did you find?carpenter ants don't eat wood, they build nests inside the wood and the wood has to be soft enough (eg rotten) to do so. again soaked insulation/rotten wood theory.toolman65
Toolman, the insulation in the new attic is all fiberglass. In the old one it's a combination of fiberglass under the floorboards, a big pile of loose cellulose around the perimeter where the floorboards were removed just piled on top of the fiberglass, and 2" of rigid foam board on top of the floorboards in the center.
I just cut a couple of holes in the drywall in the upstairs bedroom. I was more than half expecting to find wet insulation but did not. Everything seems dry and there's no discoloration or anything that would seem to indicate that it has been wet in the past.
I also tried taking some measurements with a moisture meter to try to locate any damp areas in the walls or ceiling. I figured that if I found a damp area I would cut the wallboard at that spot. But I did not find any spots that measured at higher moisture levels than others.
I'm at a loss. I just contacted an environmental engineering firm in my area. (For big bucks) they will come and measure air samples for varioius VOCs, mold, mildew, fungi, etc. I don't know what else to do so it's worth a shot.
My guess is that your insulation is soaked.
Jeff
> My guess is that your insulation is soaked.
>
> JeffThat's 2 votes for soaked insulation. I'm starting to think this too. I'll check and let you know. Thanks.I wish the internet had smell-a-vision so I could get you guys to smell this odor and tell me if you recognize it. :^) On the other hand, there's already a lot of stuff flying around the net that I'd rather not see. Adding odors to that might not be such a good idea...
Oh man! Long shot because this is an older post, but did you ever find any answers? I have what sounds like the exact same thing going on in my house (except mine was built in 2014). A lot of similarities: basement air better than the rest of the house, no mold, we put backing rod behind the staircase baseboard and it helped some but didn’t fix it. I keep wondering if the smell is the OSB or if the wall insulation has been treated with something that is forever off gassing. But why is the wall air leaking into the house? I’m at a loss and would hate to have to move with interest as high as they are right now.
Insulation soaked ... new Tyvek preventing it from evaporating.
My guess.
Jeff