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Replacing Basement Windows – Step by Step

basement windows in living room

You can replace your old basement windows by following our instructions. Learn step by step how to remove and install windows.

How To Install Basement Windows?

The first thing to do is to remove the old basement windows. Loosen the sash and carefully remove the plaster from the window joint. Then loosen the frame’s anchoring and pry the window out of the wall opening. When installing new basement windows, proceed in reverse order. First, install the window into the wall opening and align it. The frame is then attached with sash dowels and the windows are sealed with construction foam. Next, fill the window joints with putty. Finally, insert the casement of the new basement window and test: Does the window open, close and tilt properly?

How To Replace Basement Windows(6 Steps)

1. Remove Old Basement Windows

Remove Old Basement Windows

At A Glance

– Unhook the sash

– Remove plaster around window joint

– Release frame

– Chisel window frame

That's How It Is Done

To remove an old basement window, first remove the sash. Then use a hammer and chisel to remove the plaster around the window joint. Now loosen the frame’s anchoring and pry the window out of the wall opening. Old basement windows with metal frames are often screwed, glued, or clamped to the masonry.

Use a cordless screwdriver to loosen existing screw connections. If the old steel or iron connections are too rusted, knock them off with a chisel. Carefully hit with a hammer from the outside to loosen the frame. For stubborn anchoring, use a chisel or pry bar. If the window cannot be removed this way, use an angle grinder to cut the frame. If the old frame is made of wood, an electric saw will suffice.

TIP: Carefully protect the surrounding area and put in a dust cover before working on it.

2. Fit The New Frame

Fit The New Frame

At A Glance

– Clean and repair window jambs

– Insert and align the frame in the reveal

That's How It Is Done

Before fitting new basement windows, remove dirt and dust from the window reveal so that the mounting foam and mortar adhere well. Repair damaged walls in the reveal with mortar, if necessary. You can also adjust the dimensions of the window opening. To do this, measure the width and height of the new window frame and mark the corresponding values on the window reveal. Reserve about 2 cm for the joints on all four sides.

After enough curing time, start inserting new window frame. Please pay attention to the information marked by the manufacturer. New windows such as plastic windows are usually delivered complete, including frame screws and dowels. Insert the frame into the window opening, align and use the mounting wedges to fix it in the correct position: in the middle and both horizontally and vertically, use a spirit level to align well.

3. Fasten The Window Frame With Frame Screws

Fasten The Window Frame With Frame Screws

At A Glance

– Make the required drilling

– Secure the frame with screws and dowels

That’s How It Is Done

Secure the window with screws and frame anchors. Many modern plastic or steel windows already have corresponding holes in the frame. If not, drill the required holes. Plastic windows usually have a metal core, which can be drilled. For smaller basement windows, it is often necessary to fix two frame dowels on the left and right sides of the frame.

Then use a masonry drill to drill a dowel hole into the wall through the hole in the frame. Then insert the appropriate screws into the frame dowels, push them into the dowel holes and hammer them in carefully. When everything is in place, use a cordless screwdriver to tighten the screws.

NOTE: Assembly wedges remain in the joint.

4. Seal The Joint With Assembled Foam

Seal The Joint With Assembled Foam

At A Glance

– Fill construction foam into joints

– Let the PU foam harden

– Cut off excess material

That’s How It Is Done

Fill the joint between the window frame and the wall with mounting foam (PU foam) according to the manufacturer’s instructions. Consider that the assembled foam expands significantly when in contact with oxygen. After 1 to 2 hours, most of the foam has hardened enough, at which point use a cutter knife to cut off excess material. Always wear gloves when processing PU foam.

NOTE: To better adhesion and harden construction foam, moisten window reveal and window frame with water from a spray bottle.

5. Cover The Window Joint With Plaster

Seal The Joint With Assembled Foam

At A Glance

– Cover the window frame with masking tape

– If necessary, shorten the assembly wedge

– Plaster or tape the joint

– Paint the surface later

That’s How It Is Done

To cover window joint, plaster it or use self-adhesive plastic strips. Cover window frames with masking tape to reduce subsequent cleaning. Cut off any protruding mounting wedges. Depending on the substrate, prime the surface to be plastered. After enough time, apply the plaster with a spatula and smooth it with the trowel. After drying, paint the surfaces.

NOTE: For heated basements, the Energy Saving Ordinance in Europe stipulates further heat protection measures.

6. Replace Windows And Insert Sashes

 Replace Windows And Insert Sashes

At A Glance

– Hang in the wings and remove the protective film

– Install window handles

– Check function and tightness

That’s How It Is Done

Hang the sash, remove the protective film and mount the window handle. Finally, check that the windows are closed and tight. Test if the handle can be turned easily and the window can be tilted open.

TIP: Use a burning candle to check that the window is sealed after the window replacement is complete. Put the candle in front of the window: If it doesn’t flicker, the window is sealed.

Replacing more modern and safer basement windows can improve basement insulation and prevent thermal bridges and mold growth. Of course, it also plays a reliable anti-theft role.

You Need These:

– Windows with frame dowels

– Mortar

– Mounting wedges

– Mounting foam

– Primer base if possible

– Plaster

– Masking tape

– Hammer

– Chisel

– Pry bar

– Angle grinder

– Ruler and spirit level

– Driller

– Cordless Screwdriver

– Construction bucket

– Cutter knife

– Spatula

– Smoother

– Screwdriver

– Electric saw

– Metal drill

– Stone drill

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