When you are building your mancave you must ensure you have enough natural lighting to brighten up the inside to make it look more like a room than a cave. This is as important for the insulation of your building as the roof and walls because you don't want a draft that comes from a poorly fitted window or door.

Things to consider:

  • Ensure that there is at least 5mm of extra space at all sides of your windows
  • Consider how well insulated you want your windows to be
  • Keep your budget in mind as this process can cost a lot more than you might expect

Preparing the window and door slots

Firstly in the process is preparing the holes that your windows are due to be placed by cutting out the OSB that was placed over the window frame in the building the walls episode. This can be done with a saw or if you have one to hand a reciprocating saw makes the job a lot faster.

Once this can be done you can then use the same saw to cut out the wall footplate that runs over the door slot if you have not already done this.

Next, to get a perfect finish go over the cut areas of the footplate and OSB with sandpaper to smooth out any rough cuts to easily get the windows in and prevent you from getting splinters in the process.

Preparing and installing the window sills

This step requires some considering what you're doing with your build and also what style you want to go for.

Things to consider:

  • Ensure that if you want house wrap on your build that you do this before starting to install the windows, however depending on the result you are looking for, this is not always needed.
  • Have you got waterproof flex tape for the sills?

If you have used house wrap ensure that it is stapled down over the bottom of the window frame then you can cut away the excess wrap from the timber on the window sill and apply your flex tape over the bottom window frame, this is an important step to ensure that the window is fully waterproof.

Apply the flex tape to the sill and the bottom corners and the top corners, once this is done you are ready to install the sill.

Before you install the sill you need to decide if you want them stright or rebaited. A rebaited sill goes over the edge of the window this is usually a more attractive option for windows, however, it is also harder to do.

Streight sills are just cut to the exact length of your window frame and slotted into the gap.

Measure your window and cut the sill to size and use a spirit level to ensure the window is level before you use your builder's silicone adhesive to fix the sill carefully in place.

Fitting the windows

Once this is done you can start to fit the window in place with another squirt of builders silicone on the top of the sill in preparation to fit the window frame. Then carefully insert the window frame and use packers to hold it in place.

Things to consider:

  • Make sure the packers are in properly before you leave the window frame
  • Don't pack the packers in too tight to prevent damage to the frame
  • Keep the packers at least 15cm away from the corners of the windows


Next, remove the beading from the window using and hammer and chisel and lay them out of the floor as they are in the window so you don't get them mixed up.

Make sure when you do this you use the toe and heel technique, especially on windows that open.

Toe and heel:

Installation instruction | Dunster House Ltd.

With all of the beadings out of the way, you can fix the window frame to the timber window frame using the fixings provided with the windows.

Now it's time to fit the glass panels into the window, with this step each window will have a different method of fixing the glass in place depending on the brand and type of window so you will have to go off your given instructions for this step of the process.

Once this is done you can reattach the beading to the window using your hammer, it is best to use a plastic or rubber hammer to avoid damage to your glass.

Fitting your door

Fitting the door is the last step to full sealing up your man cave ready for the final touches.

Things to consider:

  • Make sure you toe and heel the door fixing as if you don't the door might lean overtime causing the door not to close properly
  • Ensure that the door frame is level on all sides

If your door frame is not level then you can use packers to level out the door frame in preparation for fitting the door.

A good idea to make the door much easier to fit is to fix the door sill to the door so it can be fitted as one as doing them separately can be hard, however, this depends on the door design.

 use the same fixing process as is required for your door, this will properly be similar to the method used to fit the window.

Next, you can use your foam gun to fill in all the gaps between the packers to give your building an airtight seal to give better insulation, this will also be a good time to do this to all the gaps in the roof and any other areas that could cause drafts.

Now your building should be insulated and free of any drafts, at this point, you will fully be able to visualise what the possibilities are for decorating the man cave and what it could be filled with.

Click the following link for episode 5: - Building the Roof