Attaching sill to block w/o core fill
I posted a question a few days ago about a sliding glass door I need to replace. The current door is installed directly on top of the concrete block foundation, flush with the level of the basement slab. Note that this is in Minnesota. There is nothing under the slider but a thin foam sill sealer. The core fills appear to be only about 1/2″-1″ thick, and are mostly cracked, separated from the cores, etc. I’m planning to add a PT sill before installing the new door – there is room under the header for the additional 1 1/2″.
My question is whether I need to fill the cores in the foundation block with concrete, and whether there is a different alternative to securing a new sill to this block since I’m afraid that the new core fills would just crack if I put screws in them. Of course I cannot put in j-bolts and bolt down the new sill since the new slider threshold will need to sit directly on top of the sill (with a jambsill in between, of course).
Any advice?
Replies
Construction adhesive. Glue it down.
the construction adhesive will work. I never saw the value of filling all the block cores in the top course until I built my first addition. I had all of the straps installed and ready for the sill and the inspector made me fill the entire top course atleast 1/2"-1" deep. The reason he gave was that Radon can come up through there and enter the house. the question that he couldn't answer for me was how it manages to get throught the 8" thick footing, but is stopped dead in it's tracks by 1/2" of the same material at the top of the block wall. His best answer was "fill it in if you want to pass the inspection." Now I know that radon is site specific, and chances are that it's not an issue on your particular home, but it's just something ot think about. Oh. He also told me that filling the cores with foam was un-acceptable as well.
Interesting. I hadn't thought about the Radon angle. If that's an issue, I've probably got a much bigger issue with the access hole to the crawl space under my mudroom (which is just a dirt floor covered loosely with 6 mil poly).
I wonder what I should fill the cores with? This needs to be a very fast job (taking the old door out and putting the new door in needs to be accomplished in a day, of course). I don't really have time to wait for concrete to set up. Anybody know of anything that would work that sets up REALLY fast?
There is fast setting concrete, but if thats the approach you want to take, then I would just fill the cores at the bottom of the top course, and use the adhesive to attach the pressure treated sill to the top of the block. I'm not cpmpletely sold on the whole radon thing. I know that it exists, and i know it can do bad things, but it was never an issue for a long time and now that homes are being built so tight, it's causing noticeable problems. I think it the crawl space is properly vented, then it shouldnt' be a problem.