Bricks and Mortar and Wood, Oh My! (long)

[MileMarkerZero]

The problem that you face is in filling a void that has no support on either side. If you use the Great Stuff first, it will expand out the outside of the hole. If you use the caulk first, you will have to let it cure before you shoot the great stuff into the hole. The caulk will cure faster than the Great stuff (1 hour to paintng for GE Silicone II vs. ~8 hrs cure time for the Great Stuff), so I would go to Home Depot (assuming it's still intact after last weekend) and get some caulk-backer rod:

http://www.homedepot.com/Tools-Hardware ... ogId=10053

and stuff it into the hole on the outside, then caulk over that with the Silicone II. After it cures, shoot the Great Stuff into the hole from the inside. After the Great Stuff cures, you can trim it on the inside as necessary. Then you can apply a thin film of caulk on the inside and paint it to taste. Or slap a piece of wood molding over the gap and paint that.

[Rick Denney]

Wade, Do Not use silicone, if it's not already too late.

Use polyurethane caulk. Unlike silicone, it is an excellent adhesive, and is cured by moisture rather than by the evaporation of an acid solvent (which is what makes most silicone caulks smell like vinegar).

I agree with the use of a backer rod.

The downside to polyurethane is that it takes a long time to cure--as much as a week. But it will cure just fine even if it gets rained on, and that's why they use the stuff for boat repairs below the waterline. It will adhere excellently to both the wood and the masonry. It will even adhere to metal.

Like silicone, polyurethane caulk will stay pliable, allowing for the different expansion rates of wood and masonry on the bases of temperature and humidity.

Once it is cured, you can backfill the inside of the wall with expanding foam to improve the insulation value, if you want. Don't depend on Great Stuff to seal in the long run. It is not caulk, and will not seal out water, which will eventually cause it so separate from the wood.

Home Depot will have it in the section that sells supplies for sealing masonry joints. I have used the stuff they say is designed for sealing joints in concrete slabs, and it works fine on all materials. It's also a gray color that is not goofy looking if any of it remains visible.

Rick "warning that polyurethane caulk is somewhat messy" Denney

[scottw]

See if you can find some "rotten cotton", a fire-rated form of batt insulation. I suggest this as a material to stuff the cracks because of it's heat-resistance [in case you ever do decide to fire it up again] and it's density--it is ideal to use stuffing a dirty crack between dissimilar materials.On top of this you can blow in a foam if you can find some means of damming it to keep it against the wall until it cures [I re-iterate--keep it off your hands!]Failing to find the rotten cotton, you can use fiberglas insulation in it's place [unfaced]. I would suggest stapling up chicken wire loosely to the area to give the foam something to latch onto as it cures. This will encapsulate the holes, ready to properly insulate the wall before you cover it with drywall.If there is a *narrow* space on the outside, consider caulking that with a paintable, adhesive caulk like Polyseamseal or Phenoseal, cleaning off all loose dirt first. This is not an unusual problem in old houses; I have encountered it many times on many jobs.
Good luck. PM, or better yet, e-mail, me if you need additional help.
Scott

[bearphonium]

No techniques or hard knowledge to contribute here; just some solid good wishes for a successful completion of first the fix-it project to deal with the surprise, and second for the ultimate completion of a repair to your specs. Good Luck!!

[Rick Denney]

Wade, it sounds like what you bought is similar to butyl rubber caulking. The only problem with it is that it will eventually get hard and brittle, but it works MUCH better than silicone. All rubber products that I have seen eventually self-vulcanize and become brittle.

If that happens, you'll be able to dig it out and put something else in its place. Silicone is nigh impossible to remove.

Rick "who sealed his motorhome windows with rubber caulking to good effect" Denney