# Install capillary break between foundation and sill



## Skip1909 (Jul 14, 2015)

I was reading an article called BSI-041: Rubble Foundations by Joseph Lstiburek on another website, about handling insulation and water management in rubble foundations. 
He writes that a capillary break between the sill and foundation is necessary to stop water from wicking up the wall and into the wood frame if you're going to handle the water from the inside. Here's how its described


> The entire house was then lifted 1 inch in order to insert a sheet plastic butyl membrane capillary break (Photograph 3)...
> Small 10 ton hydraulic jacks were used with steel angle iron brackets that were lag bolted into the perimeter foundation wood member. We used 5 jacks rented from the local hardware store&#8211;three on the outside approximately 10 to 12 feet apart and two on the inside at the lifting mid points to keep the timber rim beam from rotating.
> And no, the plaster did not crack.
> ...We did a section at a time and worked our way around the perimeter. It took two guys three days to do the entire perimeter of the house. Along the way we replaced rotted sections of timber as necessary. And here&#8217;s a news flash to the structural engineers&#8211; there were no anchor bolts.


This definitely sounds like an "easier said than done" project, and I would never feel comfortable doing this myself.
They also talk about knocking out the demising wall and replacing it with a column. Wouldnt this require the expertise of a structural engineer? 
Is any of this common practice for basement waterproofing companies? My house also has two fireplaces and chimneys that are enclosed by walls and floors, a back wrap-around deck, and a front porch to contend with.











If I disassembled the deck and removed the bottom course of siding myself, what type of contractor would I approach for the jacking?


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## JoeD (Jul 14, 2015)

Are you experiencing issues that you need to do this? 
The rubble stone foundation has probably been there for 100 years. If the wood isn't rotten yet then  I wouldn't be concerned unless you are raising the grading around the house.


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## Skip1909 (Jul 14, 2015)

Water seeps in from the basement portion walls onto the concrete slab, and moisture levels and humidity are high. My home inspector found some termite damage and noted the high moisture. I haven't bought the place yet, but the deck makes it impossible to inspect the sills from the outside.  The insides look ok from what I've been able to see, and the crawlspace area under the back of the house seems dry. The gutters have been neglected for a long time and the downspouts drain close to the foundation, so the moisture might get better once I clean all that out and extend the downspouts.  I'm trying to prepare myself for the worst


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## nealtw (Jul 14, 2015)

Like Joe indicated you usually do this work when the sill is in bad shape and needs replacing and you might find the moister in the basement is because the foundation has not been waterproofed. Good slope away from the house and some of the foundation showing above ground might be all that is needed.


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## Skip1909 (Aug 3, 2015)

Should I install a vapor barrier over the dirt in the crawlspace and run it up the foundation wall a couple inches? I don't want to encourage the water to travel up the wall and I wouldn't put the barrier all the way up the wall to the sill. Will it make a difference in the humidity of the basement? The crawlspace is unvented and unconditioned- just a leaky stone foundation.

There is an access hole to the crawlspace from the basement that is covered with a piece of plywoold and scews. Should I leave that closed off and separate from the basement area, or leave the cover off? 

There is also an old vent in the floor above the basement that has no duct attached to it. It's basically just a hole in the floor. Should i block that off so the basement air isn't coming up into the room above. Actually the room it's venting into has a fireplace and chimney with no damper. Air is free to flow straight from the basement up and out of the chimney. Heres a pic of that:


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## nealtw (Aug 3, 2015)

The hole in the floor is a fire hazard, any fire in the basement would have access to the main and give you no time to escape.
If you haven't bought the place yet, I would want to inspect behind the plywood. If the space has no vents, it should be conditioned and the ground covered butr if the floor is insulated then it should be vented.


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## Skip1909 (Aug 6, 2015)

I've looked behind the plywood, the space has no vents and no insulation. The surface of the walls is very irregular and there is no ductwork or equipment in there. The foundation appears to be unmortared large flat rocks on the inside. On the outside, the small area I could see looks to have mortar. Insulating and conditioning the space would be difficult. Even sealing a vapor barrier to the rubble would be a challenge. Is just putting down a vapor barrier over the dirt without insulating an option?


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## nealtw (Aug 6, 2015)

How much crawl space do you have to work in for height. The barrier on the ground is a must but that includes waterproofing the outside of the foundation and the venting is for the moisture that wicks up thru the foundation into the space. So we can be sure the outside isn't water tight so you will need to keep the water away from the house, slope the landscape and route the down spout water away. I haven't worked with that type of foundation but I think venting is very important but they would want to be below the level of the wood structure.


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## Skip1909 (Aug 6, 2015)

There's maybe 24-30" between the dirt and the joists. Not much room to work at all, but I'm not a big guy and tight spaces don't really bother me. There's some old construction trash in the crawlspace, like a couple of old torn up vapor barriers that were probably never sealed correctly, and some old wood molding and construction trash. 
We are closing in one week and the first issues I want to address are grading, gutters, drainage, tree cover near the house, and cleaning up the crawl space.
There is very little foundation projecting above grade at the back of the house, maybe 4-6" from the bottom of the siding to the ground, but it's blocked by the deck so I can't tell exactly. There is 3/4" crushed stone under the deck and the grading around the house looks like it's sloping away all around at least. I plan to get a string level to verify that. At the front left corner where the water comes into the basement, and where 2 gutters dump directly next to the foundation, I'm planning to dig a trench and lay a solid drain pipe down to the street fitted with a grated drain sump. There are 2 other gutters draining next to the foundation at the back (1 drains right onto the deck), which I will just put above ground hinged extensions on. 

I'm thinking maybe I can hook up an exhaust fan or dehumidifier, then (here comes the fun part) I can caulk up the band joists, and **gulp** tuck point the stones, in addition to the vapor barrier, to control the outside air coming in.
That approach seems cheaper, more DIY-able, and more serviceable,  albeit at the cost of energy efficiency, than the approach I quoted in my first post. Would it work?


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## nealtw (Aug 7, 2015)

A friend of mine has house that was designed with an insulated craw space without venting and with out conditioning. the front of the house foundation is 18ft of concrete (mountain side). All waterproofed with vapour barrier on the ground under a skim coat of concrete on the floor, all done to code. After about ten years water started finding it's way thru the wall and a terrible smell was entering the house. We found two places we could cut a hole on each end of the house hooked up a bathroom fan in one hole and set that with a timer to run for a few hours a day. That has worked fine for about five years and hopefully more years to come. And alot cheaper than dehumidifying

I would look at yours in stages, clean out the junk, cover the dirt with heavy poly. If possible seal the poly to the foundation with acoustical sealer (Black, messy, comes in caulking tube).
Cut a couple holes high in the foundation to let air flow. Insulate the floor and the plywood door, keep an eye for moisture down there. If you still have a problem, you are looking at waterproofing the outside, as that would likely be impossible, I would be trenching some distance away from the foundation and slope the top of the trench up toward the house and then cover that side with poly with a drain at the bottom. The trench would be on the last of my list and only if needed. I have seen that done between 2 houses that were close together and both had leaky basements, they ran a drain down the middle with the poly under the drain.


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