Friday, May 30, 2008

Straightening A Bowed ICF Wall

The only problem we ran into when pouring the concrete for the walls was in the tall walls above the dining room. The walls here are quite a bit taller than the braces that keep them straight, so the top four feet of two of the walls bowed out a bit after we poured them. I had anticipated this problem and put some extra 2x4 bracing on them, but it wasn't enough to stop the problem from occurring.

The problem is... if a wall bows inwards, it's fairly easy to push it out, but if a wall bows outwards, it's very difficult to pull it back in. Unfortunately, the tendency is for walls to bow outwards.

So, once I discovered this was happening, I was able to correct most of the problem with two pieces of chain and a turnbuckle. I first pushed some threaded rods through the walls, and then attached a couple of pieces of 2x4 to the outside to protect the styrofoam. Then I hooked the chain over the rods, and brought it over the top of the wall and back inside and attached it to a turnbuckle. When I tightened the turnbuckle, it brought the walls almost back into plumb. As the project progresses over the next few months, I'll come back to this problem and describe how I get around it. When the house is finished, it'll be as if the problem never occurred!

If I'd have had more chain and a couple more turnbuckles, I could have corrected the problem 100%. The biggest problem is that I only had about 30 minutes to fix it. After that, the concrete has already hardened enough so that it won't move. This was a good lesson learned. If I every do this again, I'll be more prepared.

Tuesday, May 27, 2008

The Big Day

Today we poured the concrete for the main floor walls. The pump truck arrived at 7:30 and we were done by noon. There were three guys on the pump crew; one to run the remote control to direct the pump boom, one to run the hose, and one to run the vibrator.

Due to the amount of rebar around the doors and windows, it is very important to vibrate the concrete to ensure that it flows into all the nooks and crannies. Also, in order to aid in that process, an additive called super-plasticizer is added to the concrete just before it's pumped. That changes the consistency of the concrete to make it flow better.

Everything went very well with the exception of a small problem with the tall walls above the dining room. I'll cover that in a separate post.

This is one of the anchor bolts that gets embedded in the concrete while it's still wet. They're embedded at four-foot intervals around the perimeter of the house. They are 8" long and have a hook on the end. Once the concrete cures, they will be pretty much impossible to pull out. The sill plate gets attached to these, and then the roof trusses gets attached to the sill plate.

Monday, May 26, 2008

Ready To Pour

All the wall bracing is done and everything is ready for concrete. At this point it's certainly not very pretty. It reminds me of a Mexican jail from an old Clint Eastwood movie.

Sunday, May 25, 2008

Final Wall Bracing

The last bit of bracing I need to finish is to tie the window bucks to the surrounding ICFs. Of particular importance is tying the corners to the window openings. This is done by screwing 2x4s to the window bucks and to the furring strips embedded in the ICFs. This provides lateral support that will prevent the corners from bowing outward when the concrete is poured. When the concrete is done, I'll re-use all the 2x4's for framing the interior walls upstairs.

This is another one of those tasks that took longer than expected; mostly because it's work that has to be done on top of a ladder, making it much more cumbersome.

Saturday, May 24, 2008

Ledger Board Bracing

The ledger boards that are sitting on top of the temporary walls are, at this point, only screwed temporarily to the ICFs. They can't be fastened securely until the concrete has been poured.

So, to keep the ICFs tight to the ledger boards during the pour, I've put 18" long pieces of 3/8" threaded steel rod through the ledger boards and the ICFs, and then through some 1x4 "keepers" on the outside. This will keep the ICFs sandwiched tightly to the ledger boards, hopefully resulting in a nice, straight wall at the top.

Wednesday, May 21, 2008

Beam Pockets

There will be a wooden beam installed above the kitchen near the back wall. It will support the floor joists for the loft area above the kitchen. The beam will sit in pockets that have been made in the concrete walls on either end.

The pockets are created by cutting out a hole in the ICF where the beam will sit, and then creating a "place-holder" block out of lumber, and putting that block in the hole in the ICF. Once the concrete has been poured around the block, you take out the block, and you're left with a pocket in which the beam will sit.

The wet concrete will flow behind and below the block to create a nice square pocket in the concrete. Just prior to pouring the concrete, I'll spray the blocks with a silicone lubricant so the concrete doesn't adhere to them too much. If they are really stubborn to remove, I can always cut them out with a chain saw.

Friday, May 16, 2008

Anchoring The Window Bucks

The window and door bucks need to be anchored to the concrete so that they can provide a solid frame for the doors and windows. The best way to do this is to insert a long lag bolt through a the buck into the void where the concrete will be. When the concrete is poured, it envelops the lag bolt and creates a very solid connection.

Here I'm using a 3/8 x 6 galvanized lag bolt with a large washer. I've countersunk the hole so that the head of the bolt sits below the surface and won't interfere with the window installation.

Thursday, May 15, 2008

Happy Building Inspector

I had my pre-pour inspection done today for the ICFs & rebar. Ta-da! Passed with flying colors. No defects or rework required.

Tuesday, May 13, 2008

Finishing Touches

It's been raining for the last couple of days so I haven't gotten a lot aocomplished. I have spent a little bit of time putting the finishing touches on the rebar around the windows, and I've been double-checking that everything is tied up and ready for concrete.

Thursday, May 8, 2008

Vertical Rebar

Now that the ICF walls are up, I can install the vertical rebar. When the ICF walls are being built, rebar is layed horizontally in each row of blocks. The photo below shows how the alternating rows of horizontal rebar are placed in different slots in the interior web. This allows for the vertical rebar to be dropped in from the top, and woven between the horizontal rows. This keeps the vertical rebar in place when the concrete is poured.

The only physical connection that's required is at the top of the walls, where the vertical rebar is tied to the horizontal rebar with cable ties.

Sunday, May 4, 2008

Drum Roll Please

The ICFs are done!

Wooooo-hooooo! There were times when I thought I'd never get to say those words.

Kind of looks boxy doesn't it? You just have to imagine it with a front porch and a roof.... and backfilled... and windows... and siding... and grass and flowers. It'll look much better then!

Saturday, May 3, 2008

Rain Room

About a week or so ago I mentioned about putting plastic over top the floor joists upstairs. That was so I could make a waterproof (somewhat) room for storing stuff. It's nothing fancy, but so far it's been working well.

Thursday, May 1, 2008

Wall Bracing Up

Today I finished installing the wall bracing at the front of the house. I've also got the walkway up and the guard rails installed. Now I can go ahead and finish the ICFs on the front wall.