Question:
What is the best way to seal a seal a basement DURING construction before you backfill?
CableTech
2006-03-05 03:31:57 UTC
What is the best way to seal a seal a basement DURING construction before you backfill?
Four answers:
exbuilder
2006-03-05 07:23:52 UTC
Waterproofing a basement is a misnomer. No basement is "waterproofed". The object is to control the water under and outside your foundation in order that you do not have moisture problems inside your basement. The simple answer is that most foundations are "waterproofed" by spraying the exterior of the walls with liquid asphalt. While this is essential, it is by no means the only consideration. Below is an answer I provided for a similar question not too long ago:



Don't be in a rush to backfill. It takes concrete 28 days to cure to its' maximum strength ... longer in cold weather. Backfill too soon and you are almost sure to cause the foundation to crack. While you don't have to wait the full 28 days, there are other tasks that can be accomplished while waiting for the concrete to cure.



Wait a week or more to "waterproof" the exterior of the foundation or it will just take longer for your concrete to cure since you have effectively sealed one of the surfaces.



In the meantime, your plumber should be installing the roughin plumbing that will be under the basement floor and the plumbing inspector should pass it. You should set the steel posts and beams in the basement that will support the first floor. If required, you should install plastic drain pipe around the inside of the footings and run them into the sump pump collection box. You should spread and grade the pea gravel to the height of the footers. Assuming that the plumbing inspector has passed the rough in inspection, you are now ready to have the basement floor poured. NEVER backfill a foundation before the basement floor is poured. The pressure of the backfill can, and many times will, kick in the bottom of the foundation walls ... a very expensive problem to fix.



Enough time has probably elapsed and you can now have the outside of the foundation "waterproofed". After waterproofing, you can install the perforated plastic drain tile around the outside perimeter of the foundation. It is OK to run a "T" to drain basement window wells, but DO DOT plan to drain gutter downspouts into this system. Also do not think that, just because you may have installed a sump system under the basement floor, you don't need this exterior drainage. It is an essential element in keeping your basement dry.



Make sure you have plenty of washed round gravel on site before you call your loader operator to backfill because you are almost ready.



Now it is time to make a decision. It can be tricky to backfill a foundation before the weight of the house rests on it, but it certainly is easier to construct if it is backfilled before framing begins. Some builders prefer to backfill before, and some prefer after, framing. Some will insist that at least the first floor platform be built before building (my preference). In either case, if you are not a builder, and are building your own house, try to be on site when the loader operator backfills your foundation.



A careless or inexperienced loader operator can quickly ruin all of your hard work up to this point. The operator needs to carefully and slowly dump the washed gravel over the exterior drain tile or it can easily be crushed or displaced. After the gravel is placed, you may want to cover it with a fabric barrier to impede the percolation of silt that may eventually clog your drain tile and render it useless. This is not something many builders do since it costs money and it will be many years before the problem rears its' ugly head. By then, the builder will be long gone. If you intend to stay in the home a long time, it is not a bad idea.



Whether or not you use fabric, the next step is critical. The loader operator must be careful when backfilling with loose earth. A tracked loader bucket full of earth can easily weigh several tons. If the operator simply dumps it against the wall, he can easily crack the foundation. The operator needs to "roll" the backfill in against the foundation and not be in a great hurry. If you have rocky soil, do not let the operator backfill with large rocks since he will have little control over the way they leave his loader bucket. Small rock is not a problem. NEVER let a loader operator run his vehicle over the backfilled area parallel to the basement foundation. The temptation is to let the weight of the vehicle compress the soil. This will put undue pressure on the foundation walls and will almost always cause the foundation to walls to crack. I once had to sue an excavation company that did just that. Photos of the loader tracks, running parallel right next to the cracked foundation wall, won me the case in court. After Attorney fees, it was still an expensive proposition. Normal settling around the foundation is to be expected and your finish grade will take care of settling.



One other word of advice ... don't bury construction debris in the excavation around your house. Buried wood is an open invitation to termites to attack your home. Most of the time, the finish grading is done after any bricklayers have left the job. Most builders simply let the loader operator cover over their debris. Did you ever dig around a foundation while landscaping only to constantly run into broken bricks and other construction debris? Didn't you curse the builder? You know what to do.



Good luck with your building project.
?
2016-12-15 21:45:23 UTC
Seal A Basement
Heather
2016-03-13 09:54:06 UTC
As a teacher, this is A+ and points towards extra credit! Edit: Signed, Sealed, Delivered is a song by Stevie Wonder.
LilBear
2006-03-05 13:48:13 UTC
Exbuilder (Seabee?) gave you some good advice. You should give him your ten pointer! From the retired Utilitiesman


This content was originally posted on Y! Answers, a Q&A website that shut down in 2021.
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