Insulation of floor above crawl space
我目前Hurri处理善后事宜cane Irene and have a question about my flooded crawl space and the insulation of the floor above it. . I live in in a beach community in the Northeast and and consider myself lucky that only my crawl space got flooded. My crawl space is about 4 – 4 1/2 feet high with concrete floors. It runs the whole footprint of the house so it is almost 2100 sq. ft and I do not think it is vented. Nothing is down there except my heating/cooling furnace, air vents (which are wrapped in insulation) and water pipes. The water table here is very high and water is coming up through the ground and has broken through the concrete in some spots particularly around the concrete piers supporting the house. I had about 6 – 8 inches of water and it is taking me several days to pump it out (It keeps on filling back up during high tide). I’m concerned about the insulation on the ceiling of the crawl space under the floors of the main floor since there is alot of moisture in the air. I would like to remove that insulation and was womdering if I need insulation under the floors at all. There is insulation on the walls above the concrete foundation in between the wall joists but the concrete foundation walls are not insulated. Is the insulation protecting the wood floors above it from the moisture in the crawl space? Is it saving me anything in heating/cooling costs? Any input would be greatly appreciated. I know I need to put a sump pump in (or 2) , but the back part of the crawl space is pretty inaccessible and we won’t be able to put a sump pump back there, so I think I might still have to deal with the occassional flooding. Again, thanks for your help.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
Nina,
1. The most important thing you can do is come up with a plan to address the liquid water entering your crawl space. There is no substitute for the installation of a sump and sump pump, supplemented by perforated pipe and crushed stone if necessary. (Unless, of course, you can dig down to your footings on the outside of your house and install new footing drains, sloped to daylight. It's unlikely that you can slope a footing drain to daylight if your house is on the coast and if your crawl space fills with water at high tide.)
If "the back part of the crawl space is pretty inaccessible and we won't be able to put a sump pump back there," you need to make the crawl space more accessible. That may mean lowering the floor.
2. If the insulation between your floor joists is wet, then by all means remove it and discard it.
3. Once you have made the necessary changes to keep your floor dry, you can come up an insulation plan. If you have a furnace and pipes in your crawl space, the best approach is to insulate the walls (including the below-grade walls). Here is an article that tells you how to do it:Building an Unvented Crawl Space.
Hi,
If your house is in a flood plain (not clear from the question) and you have to replace any of the mechanical systems, you will most likely not be allowed to reinstall them in the crawlspace (unless they can be installed above flood elevation).
Was water intrusion an issue prior to the hurricane? If not, then the issue might be isolated to the extreme weather and astronomical high tides.
If it is not a new issue, then you might want to explore creating an interior drain edge bed along the interior side of the fdtn walls. Remove an 18" strip of the concrete slab, excavate and install a perimeter drain that could drain to daylight as Martin suggests or to an installed drywell outside of the crawlspace.