Installing the roof windows / vents

This was a tricky part of the build as the roof windows need to sit perfectly flat on the roof in order for the sealant and adhesive to fully bond the window down making it water tight. The problem we faced was that the roof in the van had small aerodynamic groves running down the van making it difficult to find a big enough clear area to use. In the end we decided rather than position the windows in places that didn't line up (for the sake of making it an easy install)  we instead flattened the grooved areas down so that the window would sit flat on them. This was no easy task as it involved cutting many more lines in the metal work as you will shortly see. I have searched the internet high and low for ways in which other people have achieved the same result and it appears that there is no easy way of doing it and a lot of people just mount the windows on top of the groves and fill the spaces with heaps of sealant.. I wanted a slightly more professional finish to it than that! 


Once we were happy with the window placement with measured up the cut out area and transferred the measurement to the van roof using masking tape and pen marks. 


I then drilled several holes in the roof so that i could fit the jigsaw in the holes to start the cutting. 

Cutting the square out with the jigsaw was extremely easy. I had to wear ear protection and googles and the noise was so loud inside the van and the metal as it was cut would fall onto me but all easy enough to do. I had to get my Dad to hold the metal square for the last side that I cut as it wobbles around and makes it difficult to cut without someone holding it. 

Now that the square was cut we had to file down all the edges so that they did not cut us or the new window ready for the next part when we flatten out the grooves. Once the area was free from burs and sharp edges I placed the window inside the cut out square to check that it aligned ok. 

As you can see the window fits in great. The problem is that it is raised up 10mm due to the grooves so this clearly needed flattening to achieve a perfect fit.  

To flatten the groove I masked off the area I wanted to flatten and then cut a slit into the metal. The first slit I cut was in the middle however later on I learned that although this worked fine it was much easier to cut two slits on either side of the groove on the upwards bend. This cut allowed the metal to expand better when it was compressed down to make it flat.   

To make it flat I used first a small metal vice press that I had in the workshop and clamped it tight. I did this several times along the edge with masking tape underneath to get it fairly flat. I then used a G clamp to flatten down the tricky points of the grooves that wouldn't flatten completely out. Quick disclaimer here - this will take the paint off the roof! It doesn't look pretty and will need to be treated to ensure its rust proof. I felt bad each time I flattened the metal as paint would chip off. But when treated right at the end this shouldn't effect the looks or protection of the paint and after all this whole project is about a professional and long lasting finish and I believe this is the best way to achieve a flat well bonded roof window.  

I then filled down the sharp edges and made sure the whole cut out area and the clamped areas were free from loose paint, sharp edges and any other debris so that I could move on to the bonding and painting stages.  

I wanted the window to be fully secure and during the jigsaw cutting and flattening processes some of the bond from the roof to the support frame underneath had become loose. So I filled the gaps with a waterproof and fast setting adhesive sealant and clamped the areas down. This turned out to be an excellent idea as it helped to completely flatten the roof too especially over the areas I had just flattened out. While this was bonding I painted all of the areas that were damaged by the clamping and cutting with a special bare metal primer paint (this is the black stuff you can see in the images). Once that had dried I painted over it with a rust inhibitor and metal top coat paint (the white). This should fully ensure the metal is protected.

The final stage was to add the sealant to the rim of the window and stick it down. I added two tracks of Sikaflex Caravan Sealant/Adhesive to the window and another bead to the roof its self. I then mated the two together gently and checked to make sure everything was going to plan.       

Once I was happy that it was all looking ok I pressed the window down into place and gave it a gentle wriggle back and forth to make sure the sealant was nicely stuck to all the areas. 

It was getting pretty dark by this point as we had taken all afternoon to do it! (will definitely start in the morning next time!). My Dad was on the inside attaching some weights to the window frame to keep it pressing down whilst I was on the roof brushing the sealant into place. This part took about 25 minutes as I wanted the edges to look sharp clean and straight. I used a wet cloth to wet my finger and then ran it across the sealant edges making sure there was plenty of sealant pushed into all of the areas. I made sure that it was completely smooth the whole way along. 

As you can see in the below photo the front roof window fitted in perfectly! The grooves line up exactly with the shape of the window so that that it sat in place perfectly flat. I tested the window with a bucket of water and not a single leak. The areas that I flattened down and covered with paint are mostly all hidden under the window frame or sealant again adding another layer of protection to it.

I replicated this same procedure for the bathroom roof vent / window that I installed. This window is 1cm smaller than the other window and so it fitted into place with minimal groove flattening. 

The other difference with this window is that it has holes in the frame for you to screw the window down to the roof. So exactly the same as the previous window I placed sealant around the edges of the frame and gently placed it into position over the roof and then lightly pushed it down, just so that it was in the right position. I didn't want too much of the sealant coming out at this stage.    

I then drilled two holes in opposite corners and screwed a stainless self tapping screw into the hole. I then drilled the rest of the holes and did the same. 

Once all the screws were in I tightened them up to the point that the sealant started to come out the edges and the metal was fairly flat to the window frame but still leaving a few mm for sealant to stay underneath the frame to glue it down. 

Despite starting earlier in the day for this window it still took us until dusk to get it finished! I used the same trick as before, a wet cloth and my finger to smooth out all of the edges and push the sealant into position. 

The very last window to do this weekend was the kitchen extractor fan! This is a small circle hole (80mm) which has a press fitting o-ring seal. So I simply used a metal hole cutter to cut the hole, sealed it with bare metal primer then coated it with white Hammerite when dry and then put the press fitting on after that. It was very easy to install. 

And so here is the finished result! There is one more window yet to be installed over the bedroom area which I hope to do in the next few weeks.