I’m not sure how is required to fix a moisture problem to a room in a NE house that is built on sonitubes.
I discovered that a room that was added to a 1 story slab house was not installed over a slab like the building plans from the town indicated. The room sits on a series of 10 or 12″ footings that support 2×6 PT joists spaced 12″ OC. There’s no perimeter foundation and although the remodeler attempted to vapor proof the room above by installing foil-faced rigid insulation between the joists, it wasn’t done well.
Hardwood flooring was installed 1 year ago but moisture cupped all the wood in a matter of months.
I’m wondering what the most cost-effective way would be to fix. Here are a couple of ideas, some of which could be mixed and matched. I’m looking for suggestoins that may or may not include some of the ideas that I’ve had.
I thought about putting a couple of layers of plastic under the joists but that would be difficult given the footings.
I could drape plastic on top of the joists before re-installing the sub-floor and put insulation in on top of the plastic. But then I’d still have a problem with keeping the vertical cedar siding off of the ground.
I could pour a slab under the joists, after digging out some of the dirt though that would be expensive as I’d likely need a concrete pumper to get the concrete to the back of the house.
I could install a concrete block perimeter foundation and install a vent or 2 to get air to circulate under the joists. If I were to install 1 vent, I have room inside to install a 4″ pvc pipe from below the floor to above the roof to allow air to circulate.
Anyone have experience with something like this and what worked or at least what didn’t work?
Thanks,
Don
Replies
It sounds like there is not much this guy did right! Can you post a photo of conditions?
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Good idea re the picture Piffin,Here are 2 pics, 1 of the exterior footing in which you see the junction of grade and siding with one PT timber removed to reveal the footing and another PT timber still in place to the right. THe other picture is a bit fuzzy but hopefully you can make out the sub-floor that's screwed to the PT 2x6 joists and the footing underneath. You can also see that the they had attempted to seal the room above with rigid insulation but the insulation was cut too narrow and there's plenty of space for water vapor to get thru and it did.I look forward to hearing your suggestions. Let me know if you need more description or more views.Thanks very much,Don
OK, Don, the confusion in your email was because this post was to "all" instead of to "Piffin" so it never came to my attention again.In the fuzzy photo, what is the fuzzy brown stuff under the insulation?In this case, I believe the insulation is installed wrong side up. Normally it would have VB up, but that is because normally you put it on the side3 of the moisture source. but with this addition right on the ground, the source of vapor pressure is from the soil up. They should have built with slab and VB under it. I don't see any other way to make it really right. Even with PT, there are too many other problems created.How to do that now is going to call for some planning, to be able to hold the structure up while floating the crete in under it and demoing all that junk out, possibly doing soils and drainage work....I don't envy you
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Thanks Piffin,The fuzzy brown stuff is 1" foil-faced rigid insulation board. Dirt's under that. You don't see a need for a 4' deep perimeter foundation?Thanks,
Don
I don't know the soils and drainage situation there to say about deep foundation. You can do a FPSF system with foam and drainage.General principle I like to follow is to use same foundation the rest of the house has when I do an addition.That foam they used may have been a good idea had it been done well and sealed, but the foil on top then created a double VB.
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Looks like there is no room, but 6 mil vapor barrior under the whole thing sealed at edges and at the sonotubes would keep the moisture from going up.
looks like the exterior wall goes down below joists.
Cutting some vents in probably would not hurt but I would seal in winter.
6 mil poly installed properly will be amazing.
Solved my problem on a house in Northern New York.
about 1 hour and $60 and it will be fine till we pour a slab in a few years.
"The room sits on a series of 10 or 12" footings that support 2x6 PT joists spaced 12" OC. There's no perimeter foundation"
are those piers or just 8" deep precast cookies sitting on top of the soil?
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The piers are 10" and I don't know how far down they go but definitely not cookies. I'd say they go down 4' if I knew that they'd been inspected and maybe they were but I'm not sure if the inspector would have allowed no perimeter foundation. Though maybe he would have since the room was really only a 3 season room originally?
oh, and the soil shouldn't have any drainage issues - no clay around here.I hadn't heard of the foundation system you mentioned before. I Googled it - I could ask my inspector about it if it comes down to it. Thanks,
D
This looks like a "Holmes on Homes" job. There was a building inspection??
Supposedly. The addition is on file at the inspector's office tho the old inspector has retired in the 4 or 5 years since the addition was done.