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Foundation work in winter?

4K views 4 replies 4 participants last post by  Rexkwondo 
#1 ·
Im planning an addition the will have a crawlspace. Is it possible to do the digging/concrete etc in our cold WI winter? If so, are there extra costs associated? Id really like to get it started by February but I may have to wait until spring if it is not possible or costs substantially more.
Thanks
 
#4 ·
You can do it. It is done here (Minnesota) frequently. The keys are looking at predicted weather, planning and long hours once you start.

The premium is not as much as you would think if the contractor is experienced. There is some cost for heat, moving blankets around and moving tenting. Usually the daily hours (10+ ) are longer to minimize the heating and risk of weather changes. There is usually no overtime because the hours are appreciated. Because of the slower work level in the winter, contractors will usually use their best, long-time employees.

Most basement contractor have several crews, some for block and some for concrete. In the winter, two crews might work together to knock out the job quick.

They are just opening a hole for basement down the street today (high of 25-30 with no wind). The sand was delivered yesterday, dumped on a corrugated pipe for heat and covered. They will probably get much of the footings formed today. Tomorrow will be finishing forming and probably pouring. Open excavations, formed footings and poured footing will be covered with blankets. An accellerator is used in the 4000 psi concrete mix to reduce time and exposure and to generate heat. Due to recent snows, we only have about a foot of frost or less in undisturbed non-traffic areas due to the insulating effect.

The block work for the 1200 +or- sf basement will take two long days. Hot water will be picked up at the block suppliers plant early in the morning and used with the heated sand.

If the weather is above 15 or so, block will be laid without enclosures or tenting because they just get in the way. If the night is not too cold just blankets will be used on the walls AND on ALL footings. Is it is colder, then enclosures with heat will be used for the first night or two.

Freezing mortar is really only a problem if it is frozen while saturated. Fortunately, with warm sand and water, the hydration os the cement is faster and the mortar is usually not saturated after 8 to 12 hours. As soon as the temperature goes up, the cement begins to hydrate as normal, with the rate depending on the temperature and if moisture is available.

Usually, the basement will be capped with the first floor as soon as possible to get some heat into it and allow plumbing to be done.

The keys are experience, planning and getting the work done quickly once the ground is opened. The biggest problem is the ground freezing under the footings. Fortunately, with a full basement, the bottom ground is about 55 degress and temperatures can be held up quite well if blankets are used untill there is more permanent protection.

One advantage of winter construction is that good people are available due to the lower work load. Around here most other trades are slower in the winter, so pricing can be very competive if you are shopping price, but few buiders take a chance on that.
 
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