Window boards rarely get much thought until they are wrong. A board that overhangs too little, sits out of level or has an ugly joint where it meets the plaster catches the eye every time you open the curtains. Get it right and nobody notices, which is exactly the point. Here is what a homeowner should know about window boards and reveals before the second fix starts.

What window boards and reveals actually are

The window board is the internal shelf that sits at the bottom of the window opening, running from the frame into the room. In some parts of the country it is called a sill, though strictly speaking the sill is the external part of the frame that sheds rain. The reveals are the sides and head of the opening, the depth of wall between the frame and the room face.

In most houses the reveals are plastered, and the board is fitted before or after plastering depending on the job. In older properties, and in some modern builds with deep walls, the reveals may be lined in timber instead. Either way, the board and reveals are what frame the window from inside, so small errors show up clearly.

Choosing the right material

The choice usually comes down to budget, finish and how the window is used. The common options are:

MDF: cheap, stable and smooth once painted. Moisture-resistant grades are worth the small extra cost, especially in kitchens and bathrooms.
Softwood: traditional and easy to shape, but prone to knots bleeding through paint and some movement over time.
Hardwood such as oak or sapele: hard-wearing and attractive left natural or oiled, suited to period homes and anywhere plants and cups will sit.
Pre-finished uPVC or laminate boards: low maintenance and common alongside plastic windows, though they rarely look at home in older properties.

Condensation matters here. Windows are the coldest surface in most rooms, and moisture that runs off the glass ends up on the board. A board that is poorly sealed underneath or left unfinished on the edges can swell, especially standard MDF. Sealing all faces before fitting is one of those quiet jobs that makes a board last.

Getting the size and overhang right

A good board looks deliberate. The front edge normally projects past the finished wall by around 20 to 40mm, enough to give a shadow line without becoming a shelf you catch your hip on. At the sides, the board usually runs past the reveal with small returned ends, called horns, which extend beyond the opening by a similar amount.

The depth should run tight to the frame, ideally tucked into the rebate or groove on the frame if there is one. That gives a clean joint and stops draughts. The front edge profile is a matter of taste: a simple pencil round suits modern rooms, while a bullnose or ovolo edge often looks more at home alongside the skirting and architrave profiles found in Victorian and Edwardian houses.

Fitting order and doing it properly

Window boards are normally fitted at first fix stage, before plastering, so the plasterer can work down to them and leave a crisp edge. If the board goes in afterwards, the plaster has to be cut back or the board scribed to meet it, which is doable but rarely as neat. This is one reason it pays to have your carpenter involved early rather than just at the end.

A properly fitted board is packed level on firm fixings and bedded so there is no rocking or flex. Old walls are seldom square, so each end is scribed to the reveal rather than cut straight and filled. The board is fixed securely, often with adhesive and concealed or countersunk screws, and the joint to the frame is sealed with a flexible sealant rather than rigid filler, because the frame and board will move slightly with the seasons.

Timber-lined reveals and period windows

Many older Hampshire homes have deep solid walls and sash windows, where timber linings to the reveals and head were the original detail. Some even have panelled reveals or folding shutters built into the window opening. Where those survive, repairing them is usually better than replacing them, and it keeps the character that makes these houses appealing.

Where linings have been lost or plastered over, new ones can be made to match the existing joinery. This is careful work: each piece is scribed to uneven walls, the joints need to stay tight as the timber settles, and the finish has to sit comfortably with old paintwork and mouldings. Rough guide prices for this kind of work vary a great deal with the size of the opening and the level of detail, so every job differs and it is best priced after a look at the window.

Getting your window boards fitted

Window boards and reveals are a small part of any project, but they are among the first things people see in a finished room. Whether you need new boards fitted as part of a renovation, tired ones replaced, or period linings repaired, it is worth having them done with the same care as the doors and skirting around them. Take a look at our second fix carpentry service, or get in touch for a free, no-obligation quote.

Window Boards and Reveals: Small Details That Finish a Room