I’ve discovered a rotten rim joist and several ends of floor joists when R&R an entrance door. I suspected as much since the floor was slightly sunken inside the home. The failure occurred since the mudsill is essentially below grade, nothing was really done in terms of moisture barrier and the lumber was not PTL. Furthermore, a concrete slab walk up to the door was poured directly against the foil-backed polyiso- insulation board that was placed against the foundation block. The joists are 2×10 and are above the slab only 4″ putting the mudsill at approximately 6″ down.
So, the questions are:
– How can I detail this better to prevent it from happening again aside from PTL and something similar to ice guard used on roofs. I dont’ know the product’s name but I used it for around windows to flash the rough sill rather fabricating a metal tray.
– I might be inclined to add a french drain while the slab is gone (expecting to demo it and replace to gain access to the rim joist).
– There may be still another source of the water intrusion since the subfloor was rotted out, too, and I believe that’s too high for ground water to have rotted it by capilary action through the joists at the contact point. That’s another issue since I’m sure the water primarily came in from the ground. The worst area is at the door where the slab is but there is further evidence several feet away where the earth and mulch are up against the house.
Replies
A drawing would help with responses.
French drains, yes, but you need to deal with water intrusion, since it's the water held against the wood that causes the rot.
Our old house has had a lot of poor designs too - and I struggle constantly with redesign to reduce problems.
The water intrusion is definitely the focus--the french drain is just a means to carry away surface water. First, besides identifying any other source of water (potentially overflowing gutter/downspout above), I want to have a better detail of for covering the rim joist/mudsill and first course of block. That's why I mention a covering of these three surfaces in one pass with a vertical membrane of something comparable to iceguard used on roofs. I know there's something out there used for windows on new installs and it comes in various width rolls. One type can even be stretched to flash around inside corners similar to neoprene roofing. Ideally, 2-3 feet would do it.
Does this material ring a bell?
Its been suggested to regrade the yard properly and I knew that but anticipate resistance from the home owner. That's why I want a detailing of how to combat the bad situation as best as possible and leave the final decision up to them. Of course the grade issue still needs to be stated since the present condition is part of the problem. The original issue is the addition was built one course short of the existing which doesn't have this problem.
pascanale
You could try this site
http://www.protectowrap.com/products/waterproof.php
Big box store have peel and stick bitumen roofing products like this Protecto seal 45. It's about 3 times as thick as I&W. 1 Sq is $90. Or 3' x 33' roll.
http://www.protectowrap.com/products/roofing.php
Rich
That's it! I used the narrower version on windows but couldn't remember where I got it or the name. Thx
Start with regrading to get the soil level below the mudsill. Do what it takes which may include regrading the whole yard. Even if you put the french drain in, the soil will still hold moisture as well as make an easy entrance for any bugs you might have there (ie termites).
Once you're repaired your rot and before you install the door you need to flash the whole area under where the door threshold will go.
John, I've considered regrading because that's what should have been done originally and yes, it will entail a large part of the yard since its pretty flat leading up to the the problem area. As for the flashing material, I'd like to use something other than what was originally done--coil stock. I'd like to use the comparable appropriate material as what's now suggested for windows on new installs, something similar to iceguard used on roofs. I envision using this from the top of the rim joist and wide enough to finish in one width, to below grade, at least covering the first course of block. Ideally, this seal or, at least, overlap onto whatever sparging was applied onto the block foundation. Any thoughts on that?
The Ice & Water shield would work but so doe scoil stock when the conditions aren't stacked against it. But most important is the regrade. Have you checked the rmainder of th ehosue perimieter? If they screwed it up at the door, there's probably other places.
This part was an addition with the block one course shorter than the rest. The rest of the house is therefore out of harm's way. Why they built the this addition shorter isn't immediately apparent. I'm thinking through this now. The floor in the addition is lower but not by a full block and I don't believe the joists are different in depth to account for this either. Explaining this is all reverse engineering which only soothes one's curiousity. Interestingly, I didn't see any termite barrier under the mud sill either. I'm surprised the homeowner hasn't experienced more problems than this.
I think I'm good to go now. Thx