Average Labour Cost/Price to Fit/Install a Velux/Roof Window

To clarify the following prices it is recommended that you read the article in the INFORMATION box below the PRICES…

(These prices are based on a tradesman’s rate of £150.00 per day and a labourer if required at £100.00 per day. This includes the cost of buying and collecting any materials, dumping any waste if necessary and any incidental materials they will need. The minimum price will usually be for a half day)

How Much Does it Cost to Fit a Roof Window?

roof window

Fitting a mid size roof window, in a traditional (non trussed) slate / tiled roof with easy access in the loft and no other internal work.

This will take 2 men, 1 day plus timber, window + flashings £350, and inspectors fee £175………..

For your must-see guide to Tradesmen's Rates please click on the map…


A Price Guide and Information Sheet on the Cost of Fitting Velux Windows and Roof Windows

I’m sure the company do not mind in the slightest but the name “Velux” is the “brand name” of a roof window. A “Velux” is not a generic term for every kind of roof window that can be fitted, that name is er… roof window!

Roof windows

, when fitted retrospectively, are usually put into lofts. This is so that this wonderful space, can be used not just to keep the cat box and the Christmas decorations in, but as a sort of regular room.

Good idea, BUT if you are just getting a bloke in to fit the window and then doing the rest yourself, beware. Existing loft “flooring timbers” were not designed for your teenager and all his mates to use as a doss house, they are your
bedroom ceilings and if abused, they will at best crack and at worst fill your bed with plaster, soot and cosy wrap insulation, closely followed by said offspring trying to blow out his cigarette as he descends!

Get the job done properly. That will require a proper floor, a decent
ladder/stair, correct insulation, ceilings either plastered or otherwise, electrics installed to the correct specification, and of course the roof window.

This will all require the services of the
local building inspector to pass the work when it’s finished. You will legally need their involvement anyway if a new opening is being created for the window. There are unfortunately, other potential problems involved such as fire escape routes etc.

If you want the window fitted into a “
trussed” roof (as opposed to a traditional one), then its very likely the inspector will require to see structural drawings and calculations from a structural engineer stating how the relevant trusses should be cut and braced. A trussed roof is made in sections in a factory and craned into position on site, not built from scratch. However, if you have a roof window in a trussed roof space, there won’t be a lot of room to enjoy it anyway, as the loft space is usually crammed with timber.

We’ll leave the decision to you but legally you need the job supervised.

Questions to ask the builder during his quotation visit.

You should also read the article entitled
“How to Deal with Builders”

Is he aware of the correct method of installation?
As dictated by the building regulations.
Basically, after he’s taken off the relevant area of roof tiles, and removed a section of rafter, (the timbers which form the roof slope) to allow the window to fit in, he has to then make a rectangular opening by fitting two timbers, one at the top and one at the bottom. These (called trimmers) will then support the two ends of the rafter he cut the section out of, which up to now will have been floating in space.

The two ends of each
trimmer will then be secured to each of the two adjacent rafters, which to this point have taken no part in the proceedings. These will now be expected to take the roof weight, which the rafter which had the section cut away, was supporting. These are then called the trimming timbers.

I might as well finish the naming process now… the two ends of the original cut rafter (remember them floating in space)? These are called the
trimmed timbers!

Trimmed, trimmer, trimming, simple ain’t it?

Here’s the important bit now. Both these trimming rafters have to be braced to allow them to take the extra weight and not sag during the next 100 years. This is done by doubling them up. A new matching length of timber rafter has to be fixed to each of them from top (where they join the ridge board) to bottom, where they rest on the wall plate, (or the “purlin” if it is relevant).

A purlin is a larger section timber 6”or 9”x 3” (150mm or 230mm x 75mm) which is set at right angles to the rafters and underneath them. It’s job is to both support and align the rafters, (pull in).

Will he be leaving the 50 or so tiles / slates he will have to remove, behind your shed, to use as spares when the next gales hit?
(He’ll hate you for this)!

Will he be organising the inspectors visit?
You can’t, you’ll be at work.

Will he include the inspector’s fee in his quote? (Fee!.... what fee)?

Do you want him to quote for any internal work as well?
See paragraph 4.

A-Z of Job Pricing