I am going to start a new house this comming spring for a repeate costumer, I have built 2 home for him personal and 15 as referals. Now this guy is not a dummy as a matter of fact he is the only architect I have ever meet that had a vast knolegue of building homes, and knows what will work and what won’t.
This new home I going to be building for him he wants to use a block wall foundation, now I know what alot of you guys are going to say probly same as me dont. To top it off he wants to do it himself. He wants to uses the dry stak methode with a bond coat on both sides then fill all the voids with concrete.
My first consern with this is labor intensive, but this guy in one of the hardest working suits I ever met, so I dont see this beeing a problem for him. My other concern would be streingth, but if he is filling all the voids with concrete and rebar it has got to be a pretty strong wall. He wants to use a 10″ block and I have seen this done before but not the dry stack methode. I do see a advantage with the dry stack is that you can assure that you are building squar, plumb and level grade.
I asked were he had got the idea and he told me from a semmanar he attended in Eroup. He was told it had been used for 25 years and have had no mayjor issues with it to date. So what I getting at I have ben building houses for 18 years , and in that time never have I build one a block foundation let alone one like this. So if I could get some thoughts from others out their on this I would be interested in what you guys think.
Replies
I think it's a good question.
I've been wanting to ask an engineer for some time now about the difference in strength between grout filled block and cast concrete with similar rebar placement.
I tear apart a lot of concrete, and my experience is that the grout filled block has less resistance to buckling in the middle of the wall.
This might be the result of bad grout, I don't know. But if I get a hold of a grout-filled block wall with #4 bar every couple feet vertical it usually comes apart with no trouble, and it's fairly easy to snap the rebar. The same machine on a cast concrete wall does nothing unless I sawcut the wall.
The other part of the question is how much strength do you need?
Reinforced concrete it ain't gonna be. But you already knew that.
There's an underground house near here that is post&beam with dry stack infill. Don't know if the cores were filled or not. Anyhow, it's been there for close to 20 yrs doing what it's supposed to do for the occupants.
This was a schoolteacher DIY who didn't know how to lay block. Reinforced concrete was extremely unusual here at the time. He had a battle getting the dry stack method approved, but probably no more than the post&beam and grading issues.
It works. Sure isn't anything I'd be inclined to do.
PAHS Designer/Builder- Bury it!
Is this foundation a basement or a crawl space?
I have used drystack block but only for a few retaining walls. What I found was that the block were not all exactly the same size and the small variations made it hard to keep things plumb & level. Another thought is that the bagged drystack parge stuff is somewhat expensive and you end up using quite a bit of it. In my book, masons using conventional block & mortar methods don't really charge that much - around here maybe $1.25 - $1.50 a block (labor only), and they are better than most at keeping things plumb and level.
I'm all for sweat equity, but I think a detailed cost analysis needs to be done to be sure that your hard working friend won't end up working for $2 or $3 an hour. It should be a very easy comparison since footers, any rebar, block, and grout fill will all be the same materials list for both methods.
On the other hand, the customer is always right... ;-)
PS: If it is a basement, I'd allow 2 to 3 months in your construction schedule for him to DIY. One of my sub's crews of bricklayers could probably do it in 3 days using conventional methods unless it's a monster house. The thing about masonry work is that it just a whole lot of labor. When 18 guys show up to do a job it makes a big difference...
For that matter, if you do enter into a contract for the guy to DIY, I'd write the contract such that he supplies the footers and foundation, and specify that it must be within 1" of level and square. If you supply the footers, he will complain about them not being perfectly level - which brick layers or guys who do cast concrete walls are used to dealing with... He is not.
I saw one 20+ years ago.
FWIW, the technique calls for a morter joint every now and again to get stuff evened out (block aren't exactly precision made) and the fiberglass(?) fibers were too short to cover the morter joit and there was slight cracking and seepage at those points.