Short answer: Sometimes. A like-for-like swap of a standard roof window, on a roof with a sound covering and a pitch the maker allows, can often be done from the loft with the flashing dressed from a roof ladder or a short stage. A new opening, a large unit, a high or steep roof or a fragile covering means scaffold or proper roof access, and we tell you which at survey.
What "from inside" really means
People who ask whether they can fit a VELUX window from inside usually hope to avoid scaffolding, and the hope is reasonable. A roof window is lifted into its opening from either side, and the frame is screwed to the rafters or to the trimmers around it, which you reach from the loft. So much of the job really can be done indoors.
The other half of the job is weathering. The flashing is the set of metal pieces that overlaps the slates or tiles on the outside, and it has to be dressed into the roof covering by someone standing on or beside the slope. The underfelt collar and the sealing of the covering around the frame are outside work as well. A VELUX installation without scaffolding therefore means a job where the outside work is small enough to be done safely from a roof ladder, a crawl board or a short access tower, with nothing erected over the full height of the house.
Our own survey comes first, and it looks at the roof from both sides before we say which way the job goes. The overview of the full fitting day is on our hub for VELUX window installation, and this page is only about access.
When a fit from inside is realistic
Several conditions have to line up. If one of them fails, the answer changes.
- The new window is the same size as the old one, so the opening in the rafters stays as it is.
- The roof covering around it is sound and can take a ladder or a crawl board.
- The pitch is within what the maker allows for roof access.
- The eaves are low enough to reach from a ladder at ground level.
- There is a clear way up into the loft and room to work beside the frame.
The commonest example is the low back roof of a two-storey terrace or a bungalow, with a single window to swap. With the rafters already trimmed, the old frame lifts out and the new one is fitted from inside. A single roof ladder or a crawl board across the slates is enough for the outside, and the work does not need a full scaffold.
The same job is much harder on a high rear roof. Three storeys up, on a Victorian villa in Oxton or Birkdale, safe access is a requirement and not a matter of preference, and a scaffold, or a tower with edge protection, is the right answer.
When it means scaffold or roof access
Pitch. The steeper the slope, the harder it is to stand on and the more likely it is that a ladder is not enough. On a steep roof the working platform has to be built, not improvised.
Size. A large window, or a pair set side by side, is heavy and awkward to pass through the opening from below. Lifting it in and fixing the outer flashing needs people on the slope, so staging goes up.
Roof covering. Old slate is brittle and can crack under a boot, and thin natural slate on a Victorian terrace cannot be walked on safely without boards spreading the load. Plain clay tiles and some interlocking concrete tiles can also be fragile with age. A covering that cannot take weight needs access that does not rely on stepping on it.
Height. Where the working edge is high above the ground, working at height rules apply, and a ladder and goodwill are not a safe system.
A new opening. Cutting a hole where no window existed means taking off the covering, cutting and trimming the rafters and building the frame in, all on the outside. That is a different job from a swap. Rafters and trimmers are the structural part, and on a trussed roof the cutting needs a design, so the job is planned from the start with access to match. Before you plan it, check the roof window installation page for where on the slope a window can go.
What we ask before we say yes
A photo does most of the work. If you send us a picture of the roof from the street, a photo of the window from inside the loft and the label on the frame, we can say whether the job looks like a loft-access swap. The label also gives us the size, and our page on VELUX window sizes and codes shows how to read it.
Then we visit. The survey checks the pitch, the rafters, the covering and the height of the working edge, and it settles the access before it settles anything else. For an existing unit that is being swapped instead, use the steps on replacing an old VELUX window.
The price follows the survey and is written down with the figure fixed. Our workmanship carries a guarantee of 10 years, issued on paper, and any Building Control notification the job needs is sent by us. If you would rather start with a photo, Get a free quote or send it on WhatsApp.
Access questions we hear
Is the mess any worse if it is done from inside?
The dust and debris fall in the loft either way, so we cover the floor and the route down. Working from inside means the loft is where most of it happens, so clear the area around the window first.
Can I stay in the house while it is done?
Yes. A swap leaves the house open to the weather only for a short time, and we keep the opening covered between stages.
Does the access method change the guarantee?
No. The same workmanship guarantee in writing applies however the job is reached, because the flashing and the fixing are done to the same standard.