How to Frame a Basement

Average home ownership today is a mere eight year. That’s actually up, as in the decade from 2000 to 2009, it was only four years. At this time, only 37 percent of homeowners have lived in their homes for more than 10 years, according to the US Census Bureau.

One of the leading causes of short home ownership is the growth of young families. Couples starting out usually can’t afford to buy as big a home as they will need five years down the road. So they buy what they can and then when the little ones come along, realize they need more space. This often causes them to move, losing their equity in their home, assuming they can afford it.

One option to this loss is to remodel the home, adding living space. The question then becomes how to remodel it. That depends largely on what space is available. If the house has an unfinished basement in it, one of the most cost effective ways of adding space is to finish the basement. A basic finish can be done for $5,000 to $10,000, although adding bathrooms or more complexity will tend to raise the price of the finish.

This is not just an expense, as finish a basement, especially finishing it well, will add to the value of the home. Typically, 75% of the cost of the basement finish can be recouped in the form of a higher sell price, when the home is sold. However, that figure is based upon paying a contractor to do the work. In the case where the homeowner does the work themselves, they can expect to recoup roughly double their material investment, assuming the work is done as well as a contractor would do it.

Of course, finish a basement yourself is considerably cheaper than having a contractor do it. Even so, some certain precautions must be taken, because finishing a basement isn’t the same as building above ground. Certain precautions must be taken for dealing with moisture, as well as properly insulating the basement.

A Word About Concrete Basements

While concrete basements are common and are supposedly built to the same sorts of tolerances that the rest of the house is built to, a lot depends on the contractor who built the home. Building inspectors will be checking to see that the concrete floor and walls of the basement were made to the minimum requirements of the building code. They will not be checking the quality of the finish.

What this means is that the floor may not be level, may have humps and low spots and that the walls may not be even. Walls can have spots which stick out excessively or where they are indented. All this needs to be taken into account and corrected when framing the basement.

To check if the floor is level and find any low spots, the easiest thing to do is roll some marbles across the floor. They will naturally seek out the low spots and congregate there. If the low high and low spots are a problem, then it would be advisable to level the floor before finish the basement.

Moisture & Insulation

One of the big concerns about finish any basement is the potential for moist to get into the basement. Before even starting the project, it’s important to have a good understanding of how much of an issue that is for the home being remodeled. If the home was built properly, that shouldn’t be an issue, as the building code requires a moisture barrier on the outside of the basement walls.

If that moisture barrier is not in place and the walls weep moisture, it is not a good idea to try and moisture-proof the basement from the inside. Installing plastic film or a vapor barrier on the inside of the basement wall, in order to moisture-proof it is a mistake, as that will provide a place to trap moisture, which will encourage the growth of mold and fungi in the walls.

In cases where the walls seep water, a moist barrier should be installed on the outside of the wall. There are foundation repair companies who specialize in doing this sort of work and it would probably be best to contract one of them to do so, rather than attempt it as a DIY project.

However, it’s not a bad idea to paint the inside of the walls with a roll-on waterproofing compound. This will help deal with the condensation that sometimes seeps through the masonry, especially if the basement is made of cement block, rather than poured concrete. These products should only be painted onto a clean, dry surface. So before painting it on, clean off the walls and allow them to dry. If necessary put an area heater in the basement, of the kind that contractors use on jobsites, to dry the walls.

Fiberglass batts should not be utilized to insulate a basement, as they provide a great place for moisture to be trapped. Rather, closed-cell foam insulation should be used. Extruded polystyrene XPS foam board should be used, as it is moisture resistant. Not all foam boards are made to be moisture resistant. Since this board has an R-value of 5 per inch, a two inch thick foam board will provide an insulation value of R-10. That’s fairly typical for basements, as the ground around the basement provides insulation as well.

To install the foam board, first measure and cut the panels to fit. A snug fit, that slides right in is ideal. If the board has to be pounded into place, it’s been cut too long. Using a construction adhesive that is rated specifically for foam insulation, place vertical lines of adhesive on the wall, every 12” apart. Do not use any horizontal lines, as those provide a place to trap moisture. Press the panel into place and allow it to set to dry. The adhesive is viscous enough that no clamp should be required.

Run a continuous bead of caulking all the way around the insulation, as well as in any seams between insulation panels. There is also a special tape that can be purchased for sealing the seams between boards, rather than using caulking.

Spray-in Insulation

Another option for insulation is to use spray-in polyurethane foam. This is considerably harder to work with, but should be used in cases where the home has stone and mortar basement walls.

In that case, the project is considerably different, as the walls should be framed with any plumbing and wiring installed, before the foam insulation is in place. Leave the wall framing 1-1/2” to 2” away from the walls when setting it in place, to leave adequate room for the insulation.

The spray foam insulation is sprayed onto the walls, using a special spray tool. It takes some practice to get used to how much liquid insulation should be applied, as it expands while it is curing and will expand more than the novice might expect. For those who have used an airless paint sprayer for painting their home, spray foam insulation goes on a little bit faster than that.

Ideally, the foam should expand to the point just below the level of the 2”x 4” wall framing, without sticking out above the edges of the studs. If it does, the excess will have to be cut off, before drywall can be installed; so careful application to avoid that is recommended.

Framing the Walls

Before starting to frame the basement, inspect the joists overhead. Where the joists run parallel to the wall that is to be framed, it will be necessary to add blocking between the outermost joist and the sill plate for the perimeter wall. This will provide something for the top plate of the wall to be attached to. The joist end of those blocks can be nailed through the joist into the end of the block, but the sill end will need to be toe nailed into place. That may require a pneumatic nailer, as it will be a difficult angle to toe nail.

The same problem may exist for partition walls, if the placement of the joists was not taken into account when making the floor plan. But that’s really not a problem, as all that needs to be done is the addition of 2”x 4” blocks between the joists. Nail through the joist and into the ends of the block, with two nails at each end and ensuring that the block is flush with the bottom edge of the joist.

The other thing that should be done before the actual framing of the walls is to snap a line for the inner edge of the floor plate. Measure out 4” from the face of the insulation and snap a line there. That will provide 3-1/2” for the thickness of the framing, plus an extra ½” of space between the framing and the insulation. This extra ½” of space helps ensure that the walls end up straight, even if the concrete walls for the basement are not.

It’s usually best to start with the longest walls, framing them first, before installing the framing on the shorter sections. This provides the most working space. Always finish framing the perimeter walls, before framing any partition walls.

Assuming there is some floor space to work with, it is usually easier to assemble the wall section lying down on the floor and then tip it up into place. Build the wall ¼” shorter than the measurement from the floor to the bottom side of the rafters. This will allow the wall to be tipped up into place, accounting for the dimension between opposite corner of the floor and ceiling plates being slightly longer than the height of the wall. studs should be installed every 16”. For your convenience, always measure your spacing from the same end of the wall, either right or left, so that you’ll know where to find the studs later.

Framing the wall on the floor allows nailing through the plates into the studs, rather than having to toe nail two nails into each end of each stud. It’s much faster to nail through the plates, into the ends of the studs, than it is to toe nail.

If there are any windows or doorways to be made into the wall, it’s easier to frame them in, while the wall framing is being assembled on the floor. A double stud should be used on either side of any such opening. In the case of doorways, leave the floor plate in place until the wall is installed, then cut out the plate in the door frame.

Double studs, with blocks in between them, will also need to be used for inside corner, on the wall side that is raised first. The purpose of the framing is to provide something to nail or screw drywall to. Without the double stud in the corner, only one side of the corner could be nailed in place. The other would be hanging out in the air.

Stand the assembled wall framing up and align the outer edge of the floor plate with the line previously snapped on the floor. Fasten the wall framing to the floor, either with powder-actuated fasteners or Tapcon screw. Using powder-actuated fasteners requires a special tool to drive them, when can be rented, and installing Tapcon screws requires the use of a hammer drill.

Before attaching the top of the wall, use a level to ensure that it is plumb. That’s why a line was not snapped on the bottom of the joists. Use a pair of shims at every third joist, as well as at the joists which are closest to the ends of the wall, to fill the space between the top plate and the joist. Nail through the shims, and then cut off the excess. The remainder of the joists should be nailed as well, but shims are not required. Do not try to pull the top plate up to the joists in these locations; just nail them to stabilize the wall.

Look around the finished framing, trying to find any place where support for the drywall may be missing, especially on inside corner and anywhere that two walls form a “T”. Additional studs or blocking may need to be added and it’s much easier to do that while framing, than to have to stop hanging drywall to do it.

Another place where some special framing might be necessary is around any existing ductwork or drain pipes. These should fit within the walls and ceiling; but even so, it’s a good idea to check them before continuing with the rest of the project. Use a level to span the studs on either side of a pipe or duct, ensuring that the drywall will be able to make the span, without having a bulge.

basement, framing
Framed basement, David Cedrone

Finishing the Walls

Framing is, of course, only the beginning of the project; but it is a very important step. Once the framing is complete, electrical wiring needs to be installed, including wiring for television, telephone and internet, if it is going to be installed. Be sure to install any ductwork required, so that heating and air conditioning can be provided to the living space in the basement.

Drywall is then installed onto the wall framing. Most people do not bother to install it on the ceiling, but choose to use acoustic tile. This allows the possibility of getting into the space between the rafter at some later point, for additional remodeling jobs or repairs. When installing drywall, always make sure that all edges of each piece are fastened to the framing, so that there are no loose edges. Otherwise, the taping job will eventually crack in those places.

If there are places found, where the drywall does not have adequate support, additional blocking can always be installed, up until the time that the drywall itself is. There is no such thing as “wrong blocking” as long as it does its job.

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