How to fit wooden windows
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The way in which our timber windows are handled and stored can affect their long-term performance. It is important to study this guide, if you have any questions please call us.

Storm Proof Window
Storm Proof Window
Storm Proof Window

Delivery and storage

Before installation, study the ‘care of timber windows on site’ guide which includes essential information.

Step #1 (Openings)

Windows can be fitted either during construction or into pre-formed openings at a later stage. Openings can be formed during construction using either specific purchased frame templates or site constructed templates, these templates should produce openings between 10 and 20mm larger than the total window size. A tight fit of adjacent materials should be avoided where there is a danger of distortion of the frame. Fitting however should not exceed 10mm on each side.

The above applies for replacing your existing windows, measurements should ideally allow a 10mm tolerance overall (5mm each side) taken from the smallest point of the opening.

Step #2 (Spacing the window)

Before any fixings are used the window should be packed all four sides level and plum in the opening. When building-in a continuous support at cill level can be provided by a mortar bed.

Cill and head packings should be a maximum of 150mm from each jamb and beneath each mullion. It is very important when fitting to ensure the frame doesn’t become distorted as this can prevent movement of sashes, be especially careful for this problem when installing sliding sash windows.

Once packings have been fitted check the operation of all casements prior to final fixing.

Step #3 (Fixing the window)

Side fixings should be used at 150mm from the top and bottom of the frame, and a maximum of 450mm between fixings.

Windows above 1800mm wide should also be fixed in the center of the head and cill.

You can fix into the brickwork using either a screw and anchor plug or self tapping concrete anchor, ensure the fixing is at least 25mm into the brickwork, preferably 50mm. We recommend using an 8x120mm fixing (can be purchased from our website). Both the frame and brickwork will need to be drilled creating a pilot hole to fix into.

Fix the window through the frame, where possible using unobstructive locations. The fixings must be at the same point as the spacer to ensure the frame does not become distorted.

Step #4 (Sealing the window)

To prevent air infiltration between the window and the adjacent wall the gap should be sealed, this can be done using an expanding foam seal. An additional seal can then be provided by a silicone or polysulphide based sealant.

Step #5 (Decoration)

If your window is not pre-finished, finishing should be carried out in dry weather using good exterior quality materials in accordance with the manufacturer’s instructions (see ‘care of timber windows on site’ for further advice)

Step #6 (Glazing)

For advice on glazing see our ‘Glazing a timber window’ guide.

We may disclaim responsibility for any defect or failure that may subsequently occur which is attributable to non-compliance with the advice given on this information sheet.

Contact us

Contact our friendly and helpful staff

contact us

Phone: 01782 644871

Email: [email protected]


Take delivery of your new timber door in as little as 7-10 days*

Once you have placed your order with us we will contact you with a delivery date and time, our punctual drivers are always willing to lend a helping hand.


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*7-10 working days is our average lead time on un-finished bespoke windows and doors (pre-finished windows and doors may be significantly more), this may increase during busy periods.
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