Home>Discussions>YARD & GARDEN>Decks, Patios, & Porches>HELP! Would it be OK to use dirt to fill an old coal bin under part of our porch?
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Dorjer
HELP! Would it be OK to use dirt to fill an old coal bin under part of our porch?

Our house is more than 100 years old with a brick foundation, and we have begun renovating our front wraparound porch. When we removed the porch decking, we found what we believe to be an old coal bin -- about 5 to 6 feet deep, 6 feet wide and 12 feet long under part of the porch. A very old wood wall separates this bin from dirt which rises to a normal level under the rest of the porch. This wood wall continues around two other sides of the coal bin, but the fourth wall -- the brick wall of the basement -- is exposed. The wood wall facing the street is broken in one section and some dirt is seeping int the bin. An old brick and concrete block wall supporting the porch and bordering the bin is deteriorating and may be contributing to this instability. Inside the coal bin, you can see our water pipe.

We are thinking the best solution is to fill in the coal bin with dirt and rebuild the masonary wall that supports the porch. Does this make sense? If we poured dirt into the coal bin hole, could the dirt put too much stress on the brick wall of our basement? Is it OK to bury the water pipe? Does filling in the coal room sound like the best option? If not, do you have any other suggestions to do a repair that will last but is cost efficient? We are trying to maintain the character of our house and we don't want to do a porch remodel that would not fit with its Victorian architecture. Thanks for any help you can provide.

JLMCDANIEL
Re: HELP! Would it be OK to use dirt to fill an old coal bin under part of our porch?

I'm wondering if what you have is a storm shelter rather than a coal bin, you don't mention any opening into the basement.

Not knowing the condition of your basement foundation it is impossible to say if it can stand the pressure of filling the hole with dirt.

Jack

HoustonRemodeler
Re: HELP! Would it be OK to use dirt to fill an old coal bin under part of our porch?

Dirt / soil would need to be compacted layer by layer. Dry sand may be a better idea and more easily removed. Plus termites don;t like sand as they can't make mud tubes in sand,

Do check the wall for soundness before backfilling.

Mastercarpentry
Re: HELP! Would it be OK to use dirt to fill an old coal bin under part of our porch?

If you do use soil, compact it with a power tamp in 6" lifts (measured before tamping) and just tamp very lightly next to the house watching the wall carefully as you go. the tamping around it will compact the soil enough next to that wall- over tamoping might break it. When the foot of the tamp isn't sinking in more than 1/2" compared to what is around it, you can stop and add 6" more soil. When you get to wuhtin 6" of the surface soil level, stop tamping and walk the fill down as you put it in. This will approximately equal the compaction of the undisturbed natural soil around the hole.

If you don't compact fill properly (and most residential construction doesn't) it will settle and may keep on settling for up to 30 years. A vibratory plate tamp isn't suitable for this, you need a sheeps-foot vibratory roller or a 'Wacker packer" type vertical tamp. You can use a hand tamp if you halve the lifts to 3" but that's a lot of work. Unless you have experience with the type of tamp you plan on using, become aware of how to use it properly and safely- powered tamps can crush bones and feet. Hard-cap foot protectors are a good idea and OSHA required- at least use steel-toed boots and caution.

I got my Carpentry start in formwork, building factories and parking garages etc. where I learned more about dirt than I really wanted to know, as well as concrete which I am glad to know about now. The same rules apply to doing residential work correctly, but here there is almost no testing done and no training given so most of what you end up with works marginally if it works at all. Do this right and you'll never have settling to contend with.

Phil

boatmn810
Re: HELP! Would it be OK to use dirt to fill an old coal bin under part of our porch?

Is there a very light weight foam that could be sprayed into cavity ? Hoping to fill this void and push it up thru the cracks in surrounding concrete ?

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