How long do rooflights take to arrive?

Stock units and made-to-measure units

Rooflights fall into two groups for waiting purposes. The first is the standard roof window in a common size, the kind that fits between ordinary rafter spacings in a tiled or slate roof. Makers and merchants often keep these on the shelf, so the time between order and delivery can be short.

The second group is built for one opening. A flat rooflight is cut to the kerb it sits on. A roof lantern is made up from a frame, glazing bars and several panes to your dimensions. A walk-on rooflight has its glass laminated to suit the load. None of these can be taken off a shelf, so the maker schedules them into production, and the time depends on how busy the factory is.

We do not quote one figure for all rooflights because there is no honest single figure. The range for a standard roof window and the range for a bespoke lantern are different products with different timescales. If you are choosing between types, our guide to the different kinds of rooflight explains how each is made.

What lengthens the wait

Within a single type, a few choices change the time. A non-standard size moves a unit out of the stock range. Triple glazing, solar control coatings, self-cleaning glass and special tints may be built to order even on a roof window. A bespoke frame colour or a powder coated finish goes through its own process at the maker.

Opening and electric units add their own parts. A motor, a rain sensor and a wall control are supplied with the unit or separately, and the electrician needs them for first fix. Conservation rooflights with slim frames and glazing bars are made to a detailed drawing, which usually takes longer than a plain fixed unit.

Time of year matters as well. Makers are often busiest when building work is at its peak, and a lead time quoted in one season can differ from the same product in another. So the date is fixed at order, not at the survey.

Where the lead time fits in a build

On a new extension or loft conversion, the rooflight is one item among many that arrive on a date. The risk is a roof that is boarded and ready, with the opening formed, while the glass is still at the factory. A flat roof left open in that state is exposed, and a roofer who has finished the deck may have to cover the opening temporarily and come back.

We avoid that by working backwards. The builder gives us the date the roof deck or the tiling is due. We subtract the build and delivery wait, allow a margin for delivery and for checking the unit on arrival, and that gives the date by which the order has to be placed. If that date has already passed, the quote flags it, with options such as a stock alternative.

On a simple retrofit with no builder involved, the same sum applies on a smaller scale. We book the fitting for after the unit is confirmed as delivered, so there is no gap between opening the roof and closing it.

What the quote and the order confirmation say

Our written quote describes the unit, its glazing and the maker's typical range for it, with a list of what the builder needs to supply. It is a typical range, stated by the maker, and not a promise of a date. The date is firm only when the maker confirms it against a placed order.

Once that confirmation arrives, the delivery date is sent out to owner and builder, so everyone on site works to one date. If the maker moves it, we pass on the new date as soon as we hear and look at how the trades following the rooflight can be re-sequenced.

• The unit, its size and its glazing, named in the quote
• The maker's typical lead time for that unit
• The date by which the order needs to be placed to meet your programme
• The kerb or opening size the builder must work to, sent in writing
• The confirmed delivery date once the order is in

Ordering early without ordering too soon

Early is better than late, but a unit ordered before the opening is measured can turn out wrong. A kerb that is built a few millimetres out, or a rafter spacing that differs from the drawing, can make a made-to-measure unit unusable. For that reason we normally fix the size from the formed opening or from a kerb that has been checked, and we agree with the builder what is measured and when.

Where the drawings are firm and the builder has confirmed the kerb in writing, we can order from the plans. Where the structure is still changing, we may hold the order until the opening is formed. The right choice depends on how long the maker needs and how much slack the programme has, and we explain the trade-off in the quote.

What to ask your builder

If you are the homeowner, three questions keep the rooflight from becoming the item that holds up the roof. When is the deck or the tiling due? Has the opening size been sent to the rooflight installer in writing? Who will receive and store the delivery? Answers to those let us set the order date.

If you want to know who forms the opening, see our answer on who builds the kerb. For the effect of the season on the work itself, read about fitting in winter. And our rooflight installation service in Southampton sets out how the order, the survey and the fitting day are sequenced.

Related questions

Can I order the rooflight before planning is settled?

It is better to wait until the position and size are settled, because a made-to-measure unit cannot easily be changed once it is in production. We look up the rules that apply at your address and report back, and the council decides. Our guide to rooflight planning permission explains how to check.