Sunday, July 29, 2007

Foundation work continued...

Wall poured, anchor bolts installed

Control Joint Insert

Foundation pre-slab pour, ledge in foreground

Basement Slab - Lift 2 (looking west)

Concrete trucks never leave your site without dumping all of their concrete. If you're lucky it's a 1/4 of a yard or less, however the more they have the more creative they seem to get: see this blog I've been following for a classic example.

Sunday July 29, 2007
This past week's weather didn't stand in the way of progress. Since our last update, the walls were poured, and a few days following the forms were stripped. The basement slab is 75% complete and we have temporary power. We're pouring the basement slab in three lifts because of the irregular terrain and ledge that we encountered. The first pour was the lowest level of the basement, followed by a pour yesterday which isolated the ledge beneath the living room area and created a step up beneath the boys bedrooms to accomodate the rising ledge at the east end of the building site. I expect tomorrow will bring the third and final pour for the slab. The concrete sub has carefully tooled control joints in the floor slab at prescribed intervals to control cracking and we've used a 6mil poly vapor barrier beneath the slab and ledge areas to prohibit migration of moisture. They also used a power trowel on the floor which produces an extremely smooth finished surface. The remaining dampproofing (the black bituminous coating in the photos) will seal out exterior moisture usually wicked in by capillary action.

Things to attend to during your concrete pour...

1) Finished top of wall elevation. Unless you want 4' of wall exposed when you backfill this is a critical thing to coordinate with your builder. We flagged a benchmark on site to be sure we carefully controlled the exposed foundation.

2) Be sure to use control joints in walls and slabs, your concrete will shrink, it needs a place to crack.

3) Drainage beneath your slab and at the entire perimeter is essential, lots of gravel and perforated drain tile will ensure you have a dry basement. We added a drain in the center of the basement slab as well for mechanical drain-downs and unforeseen circumstances.

4) Check your reinforcing. We still utilize the basic concept developed by the Romans today because it capitalizes on steel's inherent plasticity and strength under tension. Concrete works wonderfully in compression, but is terribly weak in tension. The steel is placed in wall locations that maximize it's tensile properties and works with concrete where it is weakest. Two rows of rebar top middle and bottom horizontally and 24" o.c. vertically placed nearer to the inside face of the wall combined with a 10" thick footprint and you have a strong base to build upon.

This week: first floor framing, foundation wall insulation, and backfill. Have to be sure to brace the foundation walls prior to backfilling esp. with such green concrete.

Tuesday, July 24, 2007

Pouring and curing

July 23, 2007
The weather was ideal for pouring today. Not too hot, not too cold, overcast skies. Perfect for allowing the cement in the mix to hydrate without the water evaporating too quickly. The reinforcing looked great, anchor bolts were set, all bond outs (sleeves for routing utilities from outside the foundation to inside) were in place. The forms will be stripped in another day or two and following that the concrete slab in the basement will be poured. The concrete will be green for a couple of weeks and the initial cure time is 5-7 days. The mix we're using is a 3000 PSI mix which means if we were to test it at 28 days we would expect it to be able to bear 3000 pounds per square inch. Our concrete supplier typically mixes on the high side achieving an average of 3300PSI at 28 days for a 3000PSI mix. The concrete will continue to cure over a period of a year or more. It's critical, esp. with long walls like we have, to be sure to place control joints in the wall assembly. Control joints are joints tooled into the surface of the concrete (in our case they're small wedges placed on the inside face of the forms every 25' or so). These joints 'control' where the cracking occurs as all concrete will shrink during curing and thus cause cracking.

Only a few items remain for the foundation work to be complete. We'll be waterproofing the outside of the foundation and insulating with 2" polyiso to keep the cold out. The rim joists will receive a 2" coating of closed cell foam we're looking for R-14 and a way to seal off air movement which is the largest factor contributing to heat loss in any space. The radiant tubing beneath the subfloor won't perform very well if it's constantly battling air movement.

Temporary power service is on the way, waiting for Bangor Hydro to hold up their end of deal.

Thursday, July 19, 2007

Taking shape

Looking West

Still working on the reinforcing

add (2) #4s top/middle/bottom

A few more forms to place

One spot of ledge exposed in the basement

Thursday July 19, 2007

We're told the foundation will be poured tomorrow...not sure that's going to happen given the lack of forms, reinforcing, spot footings and two missing corners. The weather might not cooperate as well so perhaps a Saturday pour is the more likely scenario.

We ordered our windows today and expect them to ship from the Andersen factory on August 22nd. Time feels as though it's slipping away. If the pour happens in the next two days, the forms will be stripped early next week and the final slab pour mid-week.

Wednesday, July 18, 2007

Well, well, well.

July 17, 2007 : The well has been drilled and preliminary reports from Hillard Walls put it at 140' deep at 12 gallons a minute. That's flow. Just hoping for no iron or radon now.

The tailings are distinctly pink from the local granite.

Saturday, July 14, 2007

Sure footing...

Joel at work

Looking west

Light areas are exposed ledge

75% done by 10am

Resuming work on the longhouse after a week's hiatus, the foundation crew of two quickly formed the footings for our house. We coordinated the final top of foundation height on site to ensure the house wouldn't rise too far above the surrounding grade, we'll know soon enough if our calculations yielded the intended result.

We're told that the footings will be stripped tomorrow and they'll being forming the walls on Monday (July 16th) for a pour sometime next week.

Another unexpected issue arose while on site regarding the power drop from Bangor Hydro. The nearest utility pole sits about 10' beyond our property line. We're obviously not able to run buried service from that pole to our house as we don't own the property. All of this means we need to contact a line company, set a new utility pole on our property which we'll run primary power to, set the meter and continue on to the house with our buried service. Amazing what a straight creosote impregnated limbless tree goes for these days...$1000. It doesn't stop there, if they hit ledge you pay an additional anchorage fee plus guy wires for anchorage. Then the power company adds their $250 fee to 'drop' service to you on the pole that you provide. This will draw down the contingency fund but it's a great case for having one in the first place.

We're quite pleased that the groundwork is progressing and eagerly anticipate the wall pour this week.

Sig, 'throwing metal'

If only they left the keys...

Thursday, July 5, 2007

Excavation begins

Looking East - Master Bedroom in foreground

Excavation for the main volume of the house began on Tuesday and our fears of hitting ledge have been realized. The far upper right corner shows 6' from existing grade to the bottom of the hole (where we hit ledge). That will be taken up by gravel, 1' of footing and only about 5' of wall. The ledge dives down a bit in the center of the house but rises again near the dining room and living area.
Lacking the funds to blast we'll be working with what's at hand, pinning the footings to the ledge and pouring a 2" covering slab over the exposed ledge. We're counting on substantial storage area in the basement so we may raise the building out of the ground a bit more than we had planned. It's important that we maintain 4' of cover on the footings to avoid heaving issues so more fill around the house may counter the raised elevation of the foundation wall.
Hopefully today the last of the digging will take place and we'll have a better idea exactly what elevations we'll be dealing with. It's not the deep full height basement we were planning on but we're hopefully we can squeeze 6' clear beneath the floor framing.
The weather has been great and allowed the foundation contractor to get caught up and we're hopeful the forms will arrive on site soon.
Looking East - Bedrooms at far end

Center of house looking South - more elevation to work with...