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House Build Diary 7 - Laying a foundation

Before the construction can begin you need a site plan. That starts with a survey because you need to physically mark the theoretical boundaries of your property. On paper, your land will be described as some distance and direction from some physical marker like a big brass stake in the ground somewhere in your neighborhood that you have never seen. This locates some corner of your land and the rest is some shape of your property that is described on the property documents. The survey guys locate your property lines and mark them. You may be surprised to find that some fence lines are actually in your yard or a neighbor's yard and not on the line. The survey process is really interesting.

On day 105 the stake and pin part of the construction began on the MD build. There are stakes, strings, and spray-painted lines to show the crew where to place the foundation. It is important to get this correct because you have setbacks from the property lines and if you start building your house too close to the property line even if it is a few inches the inspector will force you to remove your concrete foundation and move to the correct location.

In this picture, the white line is where the outside of the basement wall will be. The orange line is the outside of the hole in the ground. The two feet of space between is the over dig so you can get in and build the basement. The over dig gets filled in after the basement walls are in place and sealed.

In the MD build we had a basement so this required some digging.

Notice the tripod with the laser level on the ground. The construction crew uses this to dig a hole with a flat and level bottom that is the correct depth.

Digging a big hole leaves a big pile of dirt. Some of it is hauled away but some needs to remain to fill in the over dig around the basement.

The other option for a house is a crawl space. It is cheaper than a basement but once you build the house you can't add the basement later. Since our lot is small we opted to have the basement and add a potential extra thousand feet of space to the house. If you are on rocky soil that might require blasting or other expensive work you may go with a crawlspace. Our first build was on a larger lot and we had all the space we needed above ground so we used a crawlspace on the TN build. The construction crew leveled and flattened the lot and dug little trenches for the footings.

The footings for the crawlspace are basically strips of concrete where the walls will be and where piers under the house will be. The concrete blocks will be the crawlspace walls. In the crawlspace, they put down gravel and then plastic to keep the moisture out of the house.

On day 107 we learned something new called root pruning. The arborist blows the dirt off the tree roots in the first foot of soil and carefully cuts the back. This is supposed to protect the tree roots from damage from being pulled and torn by the equipment.

On day 109 the concrete guys came to install the footings under the basement walls.

The concrete trucks came and fed concrete into the pumper truck in the driveway.

They got a late start and the work continued into the night using headlights and flashlights. It is helpful to have lights to use for construction that can provide good light but are not too expensive in case they are stolen or run over by equipment.

Here is day 112 after the footings were complete. The four squares are the locations of posts in the basement.

On day 121 they brought the panels for the walls and set them up.

They manually carry all these forms down and place them on the footings then hold them in place with pins and reinforce the sides with wood boards.

The concrete is extremely heavy and the forms require a lot of reinforcement.

They also build wooden forms for windows that they mount inside the concrete forms to leave an opening for windows.

Once again lasers to make sure the tops of the walls are level.

These metal tabs can hold rebar in place or just hold the forms together. They stay in the concrete and the ends are knocked off with a hammer after the forms are removed.

While the concrete is wet they go around the top of the wall and insert these bolts which will be used to bolt the sill plate to the foundation. You can start framing on a poured concrete about seven days after it’s poured when it will have 70% of its fully cured strength but it will take about 28 days to fully cure.

Removing the forms

Clearing the concrete that dripped into the window mold.

There is a window here somewhere.

On day 128 the exterior of the basement walls is sealed.

After the foundation is in pest control has to spray around it.

On day 130 they bring the drain tile which is a perforated plastic pipe and not tile. Water under the house seeps into this pipe and flows to the sump pit. The sump pump will pump it up and out a pipe away from the house.

Also, the gravel man comes and shoots gravel from his truck into the basement area and around the foundation. He carries a remote control so he can move around the site and aim the gravel. This gravel allows water to drain into the drain tile.

On day 131, our builder wrapped the foundation in plastic but I am not sure this is commonly done. The portable toilet arrived onsite.

The plumbers were on site to get the basement waste pipes in place before the basement floor was poured.

On day 135 in other non-foundation news, the crew arrived to cut down one of the street trees that the county made us cut down.

They tied a rope to the bobcat which pulled as they cut the base of the tree and they dropped it right across the front of the property. They cut it into pieces and used the bobcat to get it to the wood chipper. Then they used the grinder on the stump.

On day 138, the builder returned with a bobcat to put the dirt around the foundation but there was a problem. The fill dirt was in a big pile behind the house and the bobcat could only come in the front. There was only about a five-foot wide track beside the house which was too narrow for the bobcat to get back to the dirt. Since we were renting the house next door we were able to remove a segment of the fence on both sides of that yard and bring the bobcat in from the side of the backyard.

On day 139, they laid the plastic on the basement floor before pouring the concrete.

Some of the framing covered in the next entry started before the pouring of the concrete basement floor. They put the support posts in the basement and then poured concrete over the base of the posts. They poured around the sump pit and ejector pit which are basically big plastic buckets.

Building the basement was far more complicated and expensive than building a crawl space but it provides about a third more usable space in the house and when a house is on a small lot you have to go up or down, there is no space to go sideways or back. I should also note that there are height limits for houses in various areas. It is not simply measured from the ground to the top of the roof. You need to get someone who knows how to calculate the height limit to make sure you don't go over the limit. It is not easy to make your house shorter once it is built.



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