Products You'll Need

To complete the job in this article shop online now for the product below:

Installing the brackets and preparing the roof opening

In this five-part guide, we take you through the full installation of a Velux GGU Centre Pivot Integra Roof Window onto an interlocking tile roof using a Velux EDW Flashing Kit and a BDX Insulation Collar.
In Part 2, you’ll see how to understand the colour coded instructions, how to install the brackets to the window frame and how to prepare the roof opening, including how to space your battens and prepare the underlay ready for the window. You also see the assembly and installation of the DBX Insulation Collar.

Take a look at the other parts here:
Part 1: Unboxing the window and preparing it for installation
Part 3: Installing the BDX Underfelt Collar and Transverse Drainage Gutter
Part 4: Installing the Flashing Kit and finishing the installation
Part 5: Setting up the Bluetooth Controls

Video Transcription

Colour Coded Instructions and Installing the Brackets

So the front page of the installation instructions advises you here to look at the front of your flashing carton to determine, is there a red or is there a blue square? Because that’s going to tell you which line we’re going to work to. We open it up and this gives you your framing out sizes which will also vary compared to a red or a blue line installation. So it’s important that you just look at the flashing carton. So with all the packaging removed, you can now simply pop the window on its end because the next stage will be to fit the brackets ready for installing the window. So rather than crawling about on your knees, make life easier; pop the window on its end. Here, you’ll then be able to see the two different coloured lines that run down the side of the window. These are our installation heights and are also showing you the pre-drilled installation positions for the brackets. To determine which installation height we’re going to be working to, we can see within the front page of the installation instructions, it’s advising you to make sure you look at the front of your flashing carton, which we’ll come to a little later on. On there, you’ll see either a red or a blue square. Using that, you’ll be able to identify and correctly frame out the hole in the roof but also, this is your coloured line reference for the bracket positioning and that’s what I’m going to show you next. So if this were to be a recessed installation, you can see our bracket would be going into the side here. Now, you’ll notice there’s one larger centre opening on the section here and that’s to incorporate this tab here. You’ll also see a groove which is to allow this ridge to slot in, so if you were to fit this upside down, that should ring alarm bells and you should realise that something’s not quite right.

Don’t be tempted to hammer that section in. That’s what the groove is for. With the bracket in the right place, everything slots in and it’s nice and secure before we fix that in with the screws. You would then see how the blue line runs in line with the bracket. But because we are using the red line principle, we’re going to be following the red line around and we’re going to be inserting our bracket into the top here, like so. Take the bag of screws. As you can see, we have a variety of longer ones but predominantly shorter, 30mm screws. And all you need here are two 30mm screws for each bracket. So with a TORX-20 bit, insert two of the screws… Take the next bracket and slot it onto the opposite side, and just follow the same principle. Now, because there is no weight in the frame, we can simply flip the window over, rest it on these brackets without fear of any damage and just follow the same principle and install the other two brackets. As before, slotted into place. And then rest the window flat, because we’re ready to prepare for the opening itself.

Preparing the roof opening

So before we open up the membrane to carry on installation, I’ll just talk you through the fact that the roof has already been prepared for the window and the flashings that we’re going to be installing. The window size we’re working with is 780mm wide by 980mm high. So you can see here, our first reference point is the lower installation batten. The lower installation batten should always be installed from directly above a full row of tiles. So where possible, always try to work to a full course of tiles. Avoid having a row of cut tiles because you will always have issues dressing the bottom apron down and also being able to weather this corner in sufficiently to prevent any water ingress over the lifespan of the window. So from a full tile, what you want to do first is measure. From the instructions, you can see it shows tile to the internal face of the batten should be 80mm. So you can see this gives us a suitable gap to be able to dress the bottom apron over later on. We’ll move the tile over to the other fixing point, double check our measurement.

So like shown, we’ve still got 80mm at both ends. Our next reference point is the upper installation batten here. So with our window being 980mm high, we need to incorporate that additional tolerance of 45mm that you’ll see in the installation instructions. So from the internal face of this batten to the internal face here, we should have 1025. Again, as before, check on both sides to make sure that we’re happy that we have that 1025 on either side. So our battens are correctly positioned. We’ve also cut the battens away to the edges of our structural timbers. Also then based on our framing out tolerances of the width of the window plus an additional 30-60mm overall. So as we’ve got a 780mm wide window, we’re going to work with the maximum tolerance to give us plenty of room for insulation, plenty of room for squaring up the window and to allow the timber to breathe. So we’re going to give ourselves 30mm either side. So if my maths is correct, we should have 840mm between the structural opening. Same at the top, obviously, as you have at the bottom. Now we’re happy with our measurements, we need to open up the membrane and continue the whole installation process from inside.

So as we mentioned, everything from now on in can be done from inside; even cutting the felt. All you want to do is initially look for the junction point between the installation batten and the structure here. And that can obviously still be done from inside by just simply feeling through the felt until your finger meets that resistance against the batten. So I’m just going to now go inside and cut through the membrane. So feeling for that junction point again, just pop the knife through and start to cut down. Go over to the other corner, do the same again. And then down to the bottom. Then cut through the membrane itself and everything comes in and we can now look to just fold everything over and start stapling it neatly to the battens. So for the bottom section, you want to just pull that quite tightly to the batten. Just pop a few staples in and then we’ll trim this off in a minute. For the sides, we’re going to fold this over and again, we’re just going to keep that tight and just pop a staple just no more than about 10mm or so in from the end, so that we’re just keeping this neatly away from the structure but also it’s just going to give us a secondary barrier prior to the installation of the under felt collar itself. So to trim the top and bottom sections, you’ve got a guide in the sense that you’ve got the underside of the batten itself. So just simply rest the knife against the batten, trim across the edge. Do the same at the top. And then down the sides and again, just coming slightly past the staples so you’ve got no more than about 25mm of membrane left. And just trim that down. Don’t worry if it’s not exactly straight. It’s more just to take away the overlap so it doesn’t get in the way of the felt collar. Same on this side and we’re now ready to start fitting our insulation.

Assembling and installing the BDX Insulation Collar

So for any roof window installation, it’s important that the frame is suitably insulated to go with the insulation in the roof itself. So today we’re going to be using the VELUX BDX which is an insulation and an under felt collar, purpose made for the windows. Here, you can see from the coding how it’s purpose made because this references the size of the window itself. So it’s important to always make sure that this reference is the same as the one shown on the window carton. As with the window carton, we have the external frame size showing here in centimetres as well. Notice how we have a little red square beside the code; that ties back in with the flashings that we’ll see later on to ensure that it’s for a standard installation, hence the red line installation for the brackets.

As with the window, we have the same symbol showing no need for a knife to open this box, because here we have a pair of small tabs which enable you just to pop these open and then we can rip the box open. So just simply pop the first tab open, grab onto that and pull that up. Take the second tab and pull that down and then just simply peel the box open like so. As with the window, you have another set of instructions which we’ll backtrack a little bit to some of the sections that we’ve previously done, but the main section here is the installation of the collar itself. Inside the box you’ll see the under felt collar here which we’ll be using later on but at this point in time, we simply need these four sections here which make up the insulation collar. So I’ll put this to one side and store the box out of the way for later on. So with the insulation collar, you can see there are two longer sections for the sides and two shorter sections to deal with the width of the window. For the sides, we have suitable insulation to fill in the maximum tolerance that we allow which is that 30mm either side of the window. If you’ve only allowed yourself 20mm tolerance, that’s fine.

This soft coating here can simply be pulled away and you’re left with 20mm of insulation here. If you’ve got 30mm, obviously use it all. Anything in between, you can either peel off one side or the insulation will compress suitably. So again, if it’s 25-30mm, this will compress to fill that gap. So to actually assemble the components together, you need to peel this little corner back and that exposes the connection point for the corresponding bracket part here. So what we’re going to simply do is slide this little return on the bracket down this channel here. And you’ll see in doing so how the insulation is actually cut to shape. So as this part slides down, you just slip that into the channel and this square will pop through and lock that into place. You then simply take the second side, bring that across and repeat the process. Once those two are in, turn it around. Take the last section and as before, just pop these into place. Once these are assembled, you have an insulated frame made exactly to the size of the window. This can now be popped into the roof opening and again, following the principle of everything being done from inside, I’ll take it inside to do that. So what we do is simply feed this through the opening, flip this around, and always try to get the bottom in first because that gives you a nice anchor point against the bottom installation batten. Then just lower this in and you should find the insulation is quite a snug fit. So what you generally have to do is just manipulate the insulation a little, just to allow the frame to drop in and we’re now ready to fit the window directly inside the insulation.

New Articles