Hi all,
The first paragraph got long-ish, so skip to the second if you like…
My 1930 house has a bump-out on the back which is divided into a mud-room, pantry and closet. The blueprints show that it originally was built on piers at the rear corners. A “sill” plate runs between the piers at the back wall. There are 3 studs that run from the sill to the 2×6 header at the top. Two of those studs sit over the piers, while the third is in the middle. The whole thing was sided, orginally in bead-board, later with aluminum. A 2 ft deep by 8 inch wide concrete “ribbon” was poured, after the original construction, between the 2 piers at the back wall. For whatever reason, they did not bother to pour it up to the sill plate, so there is a 1 inch gap between the sill and ribbon. I am altering the structure to convert the mud-room and pantry into a breakfast nook, so I want to frame it out properly, so I want the sill plate actually supported by the ribbon.
I need to mix up some concrete to fill the 1 or 2 inch gap beteween the sill and the foundation (ribbon) wall. I want to use pea gravel since it will be small enough to fit in the gap. Can anyone suggest a mix? I have read (stone, sand, portland) 1-1-1, and 3-2-1. Is there any point in using lime in this mix?
Thanks,
Scott
Replies
get a bag of self leveling grout at home depot. it work great for this. Its like 6000 psi mix.
I am not sure you want to bring the concrete up to the sill plate. You might be encouraging rot and insect attack. Frequently things are the way they are for a reason.
Is there some type of failure you're addressing, or increased loads that need to be supported? If all you want to do is seal it up, expanding foam would be a better answer.
If you elect to do it, your big problem will be shrinkage. I would hesitate to try dry packing with regular portland cement, but if you do, be sure to keep the water to cement ratio as low as possible.
Call a concrete supply company, not the ready mix guys, but one that sells admixtures and tools, and tell them what you are doing, they should be able to recommend a product, or combination of products that is suitable.
To get the building inspector to sign off on it, I need to frame out the back wall to 16" on center, instead of the 5' on center that is currently there. The 10' span between the piers is esentially unsupported. The only support between the piers is the 2x4 sill plate that is 1" above the sill. Filling that gap will give me the support I need.
Possible to fill the gap with a planed or ripped piece of P.T. ? Just thinking of options.
Brownbagg is (as usual) right -- no-shrink grout is good stuff. But if you want to make concrete for some other reason;
One part portland, two parts sand, three parts gravel will get you close. If the mixture seems harsh, a little more portland will not hurt.
All things being equal, less water is better, so start out with less than you need and add slowly.
If you are so inclined, an acrylic admixture substituted for part of the water will give you much better results. This is available at any good building supply store.
Otherwise, you can also go with 50% Anti-Hydro (another admixture), it will make a very tight, water-resistant finish if you work it right.
Before you place this patch you might also consider a little bonding adhesive on the vertical faces.
Edited 12/30/2006 3:04 pm by Catskinner
Pea gravel is the worst possible choice ,fractured gravel is what you want. Dry pack is great. You mix it with minimal water. This is like slightly wet sand at the beach . If you can grab a hand full and compress it and it doesnt ooze out or cruble when you let go its perfect. Thiss is actually stronger than a mix with more water. Do what Brown bag said. Put some tarpaper between any cement /wood interfaces.
25 years in concrete , use a product called non-shrink grout, the same used to fill the gap under steel leveling plates on comm. building.. use it wet , pour it in ,steel trowel smooth, will dry in 4-6 hours 4000-6000,psi no shrink !! also use ice dam by GRACE cut into small rips to isolate wood and crete, they cannot come into contact with each other... also there is a product called SILL-PRO that is pre mixed to patch concrete floors also use a bonding agent for either application... good luck...