West of Newport by road for 27 miles, in Merthyr Tydfil county borough
Rooflight and skylight installation in Trelewis
- 10-year workmanship guarantee
- We handle the Building Control notification where notifiable
On the Taff Bargoed branch: the roofs of Trelewis
Trelewis is a small village in the Taff Bargoed Valley of south-east Wales, in the southern part of Merthyr Tydfil County Borough. A freight-only railway line runs through the village, the Taff Bargoed branch, which opened in 1876 as part of the former Great Western Railway and Rhymney Railway. It carries coal from the Ffos-y-fran opencast colliery.
The table below goes by general house type. House types vary: a pitched roof over the main rooms, sometimes a lower roof behind, and a loft that may or may not be boarded. A roof window can be the way into that loft, and a flat rooflight or a sun tunnel suits the parts a roof window does not reach.
| What you own | What is overhead | What to look at |
|---|---|---|
| Terrace or semi with an old VELUX window | Pitched roof, window set into the slope | A swap for the same size, or fresh glazing in the frame |
| House with a loft room in mind | Pitched roof, timbers to be checked | A new opening for a roof window, with its approval sorted first |
| Shallow roof over a porch, garage or lean-to | A pitch low enough to need the right product | A product made for that pitch, picked from the maker's range |
| Home with a flat-roofed extension | Flat, on joists | A flat rooflight over the room that needs it |
Three starting points for Trelewis homes
11:00
Merthyr Tydfil council and a rooflight
Merthyr Tydfil County Borough Council decides planning questions for Trelewis. Merthyr's conservation areas include Treharris. Only the council can place a particular house inside or outside a boundary, and its historic environment pages are the start. Inside a conservation area in Wales, adding a rooflight to the roof slope of a house falls outside permitted development and needs a planning application, and the Wales planning guide covers the remaining tests.
Flats are outside the householder rules altogether, and a council can withdraw rights from a house by an Article 4 direction. For a listed house, the thing to know is that listed building consent depends on the effect on the building's character, and the council is where it is sought.
12:00
Villages and towns around Trelewis
Misted glass at breakfast
When the pane in an older roof window has clouded.
In early autumn the first sign can show at breakfast, when daylight from the sky makes every flaw in the glass easy to see. One pane in a roof window looks cloudy while the one beside it is clear, and wiping the glass changes nothing because the haze is inside the unit. The choices behind it are worth laying out. Nothing here needs to be decided in a hurry, and the survey is free.
Write down what you can see before you get in touch: which windows are affected, whether it is one pane or both, and whether the sash still opens and closes cleanly. Those notes help decide between new glass and a new window, and they put some detail behind the first conversation.
The glass can come out on its own, or the whole window can be replaced. Which is right depends on the window. Our guide to a sealed unit or the whole rooflight explains how to decide, and the page on swapping only the glass of a VELUX window shows what that looks like in practice.
The Building Regulations see the two differently. For the energy rules, fitting only new glass into the frame you already have does not count as building work, while a window or roof window replaced like for like is still building work. Where the work is notifiable, we handle the notification with local authority building control or a registered building control approver.
The new glass is a chance to improve on the old. Among its glazing choices VELUX has an easy-to-clean coating, an inner pane of laminated glass, there so that an accidental break does not drop shards into the room, and a choice aimed at cutting the sound of rain. Whether a given window can take any of them varies with its model and glazing, so we check that before suggesting one.
If you can, find the type sign, the metal plate on the upper edge of the sash, which shows when the sash is swung open. VELUX says windows it made after 1968 carry one, and its code gives the size, which helps before deciding between new glass and a new window.
Clouded pane, roof window
- Choice
- New glass in the frame, or a whole new window
- Frame kept
- No building work, for the energy rules
- Whole window
- Building work, like for like
- Glazing options
- Depend on the window and its variant
Match what you already have
Reading a VELUX size before anyone climbs a ladder.
Measure nothing yet. Find the type sign first. It is a small metal plate on the upper edge of the sash, there to be seen when you tilt the sash open, and the code on it names the size. VELUX publishes a table of its codes with their widths and heights, and MK04, MK06 and UK04 are three of them.
A matching size keeps the job small. A replacement of the same size can leave much of the finish around the opening where it is, while a different size changes the opening itself, which is why the size question comes before the style question.
Roof windows come in standard sizes, so a like-for-like swap is usually a matter of finding the same code and checking that the opening is still sound. If the code is worn, a photograph of the window and a measured width and height from the inside will do. The VELUX size code guide goes through the codes in more detail.
Deciding on a bigger window than the one you have is a different job. A wider window can mean cutting into the rafters, and a taller one raises questions about where the window sits relative to the room below. The survey looks at the timbers and the slope before any answer is given.
The type sign is the reference for all of this: VELUX publishes UK04, for instance, as 134 cm across and 98 cm tall, so a wide window is easy to confirm before anything is ordered.
Two windows side by side deserve a look together. A pair put in at the same time is the same age, so if one has clouded the survey checks the other, and a single visit can cover both. Open each sash on a dry day so the type signs can be read, and note any that are hard to see or faded.
For a new roof window in Wales, we handle the Building Regulations notification where the work is notifiable, which saves you the paperwork. The guide to VELUX and Building Regulations in Wales covers what the regulations ask of one.
| Code | Width | Height |
|---|---|---|
| MK04 | 78 cm | 98 cm |
| MK06 | 78 cm | 118 cm |
| UK04 | 134 cm | 98 cm |
Not quite flat, not quite pitched
Choosing a product for a shallow roof over a porch or lean-to.
Think of the room first, then the roof. A porch is a place you pass through, a utility room is a place you work in, and a converted garage may become a bedroom. Each wants a different amount of light and a different amount of privacy, and the glass is chosen after those answers, not before.
Between a flat roof and a properly pitched one lies a band where product choice matters. A porch, a garage conversion or a lean-to behind the house can have a roof that is only slightly inclined, and the glass has to be made for that pitch.
For its own products VELUX names a pitch band each: the flat roof dome is for roofs between level and 15 degrees, and the low-pitch roof window for roofs between 10 and 20 degrees. The ranges overlap, and which product fits a given roof depends on the measured pitch and on what the room needs. A guess from the ground is not good enough, so the survey measures it.
The other products come with their own advice. A kerb sloping at 5 degrees or more, Rainclear advises, helps minimise water pooling on its flat glass rooflights. That is Rainclear's advice for its own product, and it sets no rule for anyone else's.
A roof between those VELUX bands is where measuring pays off. With the flat roof dome given 0 to 15 degrees and the low-pitch roof window 10 to 20 degrees, a roof measured at 12 degrees sits inside both ranges, and one measured at 18 degrees sits inside only the second.
Pitch is the angle of the slope from the horizontal, and a roof that looks flat from the road can carry a few degrees. That small angle decides which products are suitable, which is why a tape and a level come to the survey and a guess does not.
When the light fades in the evening, the glass over a porch or a utility room starts to show whatever is lit below it. A tidy lining makes that a calm dark panel. Say at the survey if the room is used in the evenings, and we plan the lining to suit.
If the roof is a flat roof over an extension, the flat roof rooflights page is the place to read next.
About Trelewis roofs
Which council deals with planning in Trelewis?
Merthyr Tydfil County Borough Council. Its conservation areas include Treharris, and for any address the council is the place to confirm whether the house stands inside a boundary. The Welsh planning rules show what follows if it does.
What size is a VELUX MK04?
VELUX lists MK04 as 78 by 98 cm. Look for the code on the type sign on the top of the sash, and if it is faded, tell us the measured width and height.
Why do shallow roofs need a different product?
Each maker states the roof pitches its products are designed for, and a porch or lean-to may sit outside the range for an ordinary roof window. We measure the pitch at the survey and match it to the maker's range, so the product we suggest is one its maker designed for that roof.
Can a loft room in Trelewis get its first roof window?
It can be considered. A new opening in the roof generally needs Building Regulations approval, and we handle the notification where the work is notifiable. Whether planning is needed turns on the house and the land, so start with the Welsh planning section.
My Trelewis home is a flat. Where do I begin?
Householder permitted development rights apply to houses only, so a flat or maisonette has none; the planning guide covers houses. Tell us the roof and the room when you get in touch.
Is the survey free in Trelewis?
It is. From Newport it is 27 miles by road to Trelewis, a small village in the Taff Bargoed Valley in the southern part of Merthyr Tydfil County Borough, and a fixed written quote follows the survey.
Where should I send a photo of my old window?
To WhatsApp 07880 284133 or info@supremeskylightsnewport.co.uk. Include the room it lights and, if you can, the type sign. The survey form is there if you prefer it, and a photo helps whichever route you take.
Book your free survey
10-year workmanship guarantee.
Building Control notification handled where notifiable.