VW T4 Hightop Roof Fitting

As with many of my ideas this started elsewhere. We were planning a couple of trips and would want the bikes on the bike rack so would not be able to use our external box so I started looking for roofboxes this was pretty hard as there didn’t seem to be anything cropping up second hand.

I guess this is the type of thing you buy and leave in the shed or garage all year and just use it a few times. I was specifically looking for something big enough for snowboard in winter and hopefully big enough for my surfboard too so made the search much harder, with the trips coming up I moved my search to new roof racks and roof boxes and the costs are just a bit crazy the cheapest I could find was £350 and that was not an option.

We left the bikes at home and put the storage box on the bike rack for the trip and I really started looking into the idea of fitting a hightop as it would give me the extra storage that I wanted as a bonus I would have that storage all the time. Just to make things even easier to decide, it wouldn’t cost me much more to get a hightop than the initial idea.

I made the phone call to a local Cornish company Shapes GRP and placed my order. They answered all my questions and were able to make it in time for me for a work trip down south. One of the main questions I had was whether they paint their roofs to match your colour which if that was the case I would just spray it myself but they can match the gel coat which is far better as you are not so worried about scratches or damage.

All went smoothly and the roof was delivered to my parents house ready for me to fit it. Which takes us onto the first step of trial fitting the roof, this was a bit of a scary moment as there seemed to be a slight bow the rear seemed too wide and one side had been overcut not leaving a very tidy gap.

So Step one was to improve the fit on the left rear I used some masking tape to get a rough shape of how much fibreglass I needed to add. I could then take the roof off and use some fine metal mesh cut to shape and epoxied on to give me a backing for my repair. I then used Polyester Fibreglass Filler to fill against the mesh to build back the area. I could then fit the roof mark and re-cut closer to the shape. Finished up with sanding and paint. I had left my colour matched aerosol in Scotland so had to use a Gloss white for now.


Shapes now use an old T4 roof so scribe this for you improving the fitment and not needing to make modifications yourself.

Now happy with the fit and happy the slight bow would disappear when attached I worked out I could use ratchet straps to pull the roof down and wood wedges to pull the sides in while the sikaflex was bonding. Onto making a hole in my brand new roof now to fit a Fiamma Roof Vent. I measured the centre of the roof and parallel a few times and also got my dad to re-check it a few times as I didn’t want to get this wrong. Once happy, four pilot holes and connect the dots with a jigsaw. The roof vent drops straight into the hole with a small seam of silicone to make sure everything is watertight. Holes were drilled through the roof as these then allowed the vent to be screwed through to a wood frame sandwiching the GRP roof. I added a dab of silicone to all screw holes as well so hopefully no leaks appear in that region. One error at this stage was the 45 degree angles on the wood frame meant the corner screws were not as secure as they could have been.

That was it the roof was ready to fit, with another lesson learnt later that this would have been a good time to insulate and carpet the roof as its pretty hard work when in situ. Now time to cut the old roof out first removing all the roof lining any old wiring looms for the interior lights and the sunroof I had fitted. I know a lot of people have problems with the roof fixing’s But I have always used an oversized torx bit which I wedge inside and can then just unscrew each one and remove.

This is where there is no turning back and time to cut the roof I have decided to remove the lot and wanted a well over 6ft bed I would need to also cut a small part out over the cab to allow room to climb into the bed. This meant taking out all the roof supports which one was saved from the scrap metal pile and extensions welded to each side so it could be riveted back in further up the van.

I had also chosen to cut the roof right to the rain gutter which is double skinned and could then be re used as the bed board support. I found the easiest way to remove the roof supports was with hand metal shears I would have loved to have used grinder or air grinder but with interior still in place didn’t want to risk it. I used air shears to begin with on the main roof panel but found with the cut I was needing in the gutter they would be no use and I moved onto a jigsaw to cut the rest out.

This wasn’t too hard as I didn’t have to mark anything out I could just follow the lines of the roof to make my cuts. With all the sharp edges I used a file to remove the sharp edges and burs, painted all bare metal and added a layer of duck tape to save me any pain moving around.

Things are certainly happening at this point and with a massive convertible it was time to get the roof on again a test fit and minor adjustments to get it sitting even all around I then used masking tape to mark where the roof would come to.

I could then lift the roof up onto long wooden slats to allow me to use sikaflex 221 to run a bead around the entire area that it would be bonded to, above the tape line. I only used 1 and a quarter tubes for this then used the remaining from the inside to fill up any areas that could use some more.

Once lowering the roof onto the sikaflex you could feel the immediate grab it had and you could walk around and just push the roof to where it needed to sit and apart from the rear it was seemingly holding itself in place from that point. As security though I added some long lengths of wood and clamps to hold the front portion in place and used the ratchet straps and wood blocks to pull the rear into place.

I couldn’t find anything clear about the sikaflex 221 apart from leave 24 to 48hours to dry. So I left the straps and clamps on for six hours which left no movement once removed and all seemed solid. I then got the services of my brother ( who is a tiler ) to finish up for me and just use a white silicone around the outside to smooth the transition between van and roof and cover the fibreglass edge. I much prefer this to the rubber trim that I see used a lot and I am sure doing it this way must give more of a bonding surface.

Next up I will write about the interior and what my plans were with that.


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  1. Sam clark says:

    Hey. Love the blog! Just wondering what you did with the interior? Did you fit a strengthening frame at all? Really want to do my own high top but can’t find any details about the frame. Any advice would be appreciated! Thanks


    • will says:

      I did reuse one of the existing roof strengthening bars at the front although the roof will add a lot of the strength back I would guess the frames are more for pop tops where there is just a hole.

  2. Jason says:

    Hi I’m thinking of doing this to mine but I do like my rear spoiler on my tailgate. Will I have to remove the spoiler? Or will the spoiler still be fine?


  3. Bill says:

    looks good
    do you have full head height at the rear of van?
    I would like to do this with my t5, but cant find a roof that I like the look of, I think the roof you have suits the t4 really well.
    All the best Bill

    • will says:

      No full head height at the rear but seating is there so wouldn’t be able to stand there anyway. The roof does really suit the van but think it would also be nice to have that full height all the way back.

  4. Lee White says:

    Great blog!
    Its nice to see someone take pride in something.
    Can I ask how you came to use Sikaflex 221 as the sealant? Were you recommended this?
    Also looking at your photos am I right in thinking you can cut as much or as little out of the roof, depending on what the individual wants?


    • will says:

      Hi Lee

      A Google recommends Sikaflex 221 for this application then to back that up I read the datasheets as well to confirm how and where to use it etc.

      Yes you could certainly cut the entire roof out or even just a small space the more you cut means thinking about adding some sort of bracing back in.

  5. Elaine Barr says:

    Love the blog, very informative. Did you look at any other roofs/companies as I am trying to find a GRP high roof for my van.

    • will says:

      The place in Truro was close to my parents house so that made most sense for me, I have heard there are a couple of other options but not seen them actually for sale so can’t help you out sorry.

  6. lee white says:

    hi Will,

    Thanks for your reply. is it possible to get a contact number for yourself so I could have a chat regarding fitting of the high top. if you want to email me that is fine.



  7. mat says:

    Hi Great info thanks. I just picked up my roof today from Truro a 1600km round trip! I will be using your guide as my bible.
    Thanks Matt

  8. matt says:

    Hi Will.
    Fitted roof as above. Had a problem with one rear side bulging out 5mm more than it should, otherwise looks great. Just one question re insulation. Which foil insulation did you use? I put on foil bubble type and was wondering is it enough.

    • will says:

      I used a self adhesive foam foil backed insulation certainly seemed to keep a good amount of heat in. and snow on roof didn’t melt to fast when heater was on inside the van.

  9. Chantal says:

    Was it just Sikaflex you used to hold down the roof to the body? or did you use bolts to also screw it in place or maybe a brace piece to keep the high top to the van body?

  10. oliver richards says:

    Awesome stuff! I actually did this to my t4 four years ago now. Everyone thought I was mad!!! the fit from grp wasn’t that best and I had to do the same with epoxy too. Once im back from Aus ill buy another t4 and do it all agin for sure!!!

  11. Christian Perez solar says:

    Hello thank you for sharing this info
    I have Installed my hightop same way as you did. But I was wondering if you have any pointers on the interior. I find it hard to visualise how to make the covers attached to the metal and the wood frame.

    • will says:

      I glued my carpet lining directly to the insulation which was self adhesived to the side of the roof. I also glued a couple of wood tabs to the fibreglass roof so I could screw the front panel on.

  12. Christian Perez solar says:

    Thank you very much for your answer this gives me a good perspective on what I need to do next. Thank you.

  13. Anthony says:

    Hi Will,
    I was wondering how the high top roof was fairing after a couple of years.
    Any issues or things that could be done better? I’m considering doing the same but still weighing up the pros & cons between pop top and high top.


    • will says:

      I have sold the Van but I did actually bump into it a month ago and all still looked fine. Differently I think I would have prefered a hightop all the way back without the step down as you lost a lot of room because of that. Also I would carpet line it before I fit it to the van either the same method or by glueing wood tabs and using wood panels to carpet and fit in.

  14. jon sutherland says:

    hi where did you buy the top?

  15. Dante says:

    Hi. Im looking at buying a roof from shapes, however they could not answer what the headroom would be. I’m 1,92cm and im afraid it would be tight after insulation. Do you know what hight you have inside?

    • will says:

      I can see how that would be impossible for them to answer as depending on your floor height and insulation in roof you could potentially loose a lot of height. Im just over 6ft and could stand up although I would hit my head on the frame for the vent which I should have mounted flush on the inside and raised on the outside. I would say you being taller you would be just about grazing your head.

  16. Pete Colley says:


    I’m awaiting delivery of my HiTop from Shapes at the end of May. I plan to fit it myself to my Vivaro 2012 LWB.

    Really helpful blog : thanks

    1 Can you tell me how you insulated your roof and with what materials

    2 Same for finishing – carpet or what?

    3 I see you fitted a roof vent. Did you consider side windows in the HiTop? Any thoughts appreciated

    • will says:

      Hope the fitting went well, I used adhesive foam to insulate and stuck carpet straight to it. I don’t think I would do it that way again. The next roof I did I glued batons to the side and cut ply panels to line with carpet and then used bottle insulation behind.

      I think if it suits your use side windows are the way to go they will open up the van massively, I was using the van in cold places so didn’t want more places for cold to creep in. I have fitted a massive skylight roof window to one though and that was ACE felt like the hole top was open.

  17. James says:

    Great write up, I’m looking to do this myself as I have been quoted £1000 for the fitting alone.

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