# Sealing Midi Heki Rooflight on profile metal roof



## Firefox (Oct 15, 2009)

I need to seal the rooflight against the corrugated roof profile in a new build. Normally the Heki or Fiamma lights are sealed against a flat surface with a thin gasket and sika mastic. On my roof, the van has a 20mm corrugated profile in the steel for strength. So I need a foam rubber or hydrophilic gasket strip wich can be compressed to take up the 20mm difference in thicknesses, which will seal the rooflight against water ingress in combination with the mastic. Any ideas where to source such a sealing strip gasket product in the UK?


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## chopper (Oct 17, 2009)

you have to build the gap up with mastic strip then clamp the roof light to it then a smear of silicone around it job done they say 

ive got to do mine but hesitant a bit lol


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## Firefox (Oct 20, 2009)

Well a dearth of replies on this one.

This is what I have found out by various research:

Either 

1. Choppers solution (see above)

or

2. Build up in between the ridges using UPVC plastic sheet (eg Fascia board etc) of a thickness to match the depth of the ridges (typically 10-20mm). This presents a flat surface for the rooflight to sit on. It is then stuck down and sealed with mastic in the normal way. The UPVC is stuck with Sika mastic or similar. The roofflight bolts are drilled through the upvc and the metal skin of the roof.

or

3. Ignore any mastic strips or UPVC build ups, and just use loads of sealant. to make up the gap. Personally I wouldn't do this for a ridges profile bigger than 20mm.


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## chopper (Oct 20, 2009)

this is the stuff ive heard you need to use 
have a read see what you think may be worth a phone call or message to ask 
CARAVAN MOTORHOME 40MM OR 20MM SEALING TAPE MASTIC on eBay (end time 21-Oct-09 16:42:23 BST)


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## Firefox (Oct 20, 2009)

As you say, probably worth checking. I think 20/40mm is the width. The thickness would be say 3-5mm (guessing by pic) so to build up the profile gap you would need quite a few layers of tape, say 4 for ridge profile of 16mm. But presumably the strip will stick to itself quite well so it looks quite a good solution. 

Probably would use the 40mm wide tape to provide a good wide base. Could even include a layer over the top of the ridge profiles to give the same resilient flat surface all round.

PS: One guy told me that with the metal ridges, if you put a rooflight in it leads to "damming" of the channel between the ridges and then standing water. To avoid this it is best to have the  rooflights central on the high point of the roof so the water drains off either side.


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## freelanderuk (Oct 21, 2009)

have a look hee you may find something   door seals, rubber seals, rubber extrusions, window rubbers by seals direct


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## Readytoroll (Oct 21, 2009)

How about this from wickes?


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## Firefox (Oct 21, 2009)

^
That's amazing, I was looking at exactly this stuff in Wickes only a couple of days ago! Unfortunately the profile of the corrugations on the plastic sheets are nothing like the profile on my roof. My roof corrugations are like 12x20mm bumps at about 100mm centres. Nevertheless I think this stuff could be used one used a couple back to back as they are packaged with the wavy bits meshing with each other, but sika mastic sealing the wavy interface. This type of closed cell foam can form a good seal if sufficiently compressed. I believe this is the way Timberland do it, as I asked the Timberland rep at the NEC show how they do the Renault Master roof and he said a sqidgy foam material and mastic. It would be nice if Wickes sold these in longer rectangular strips without the wavy bits.


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## GARY ENGLISH (Oct 21, 2009)

*sun roofs*

Had this problem on the old bedford cf.Had some alluminuim strips cut to fit in the recess,then just sikaflexed them in place.Did several never had an leaks.


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## GillRuss (Jan 5, 2010)

should there be a frame in the cut out to screw the light to ?


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## l77 tuf (Jan 6, 2010)

trust me go down to caravan suppliers like harringtons/glossop caravans/towsure any big outfit and buy the correct sealent and you will never have trouble i self build with my dad and use the proffecianal stuff its liek chewing gum on a roll you dont need any sealent then we use on all our windows/fridge vents/roof lights/any holes you cut in the side of your van use it mate its £5/£7 a roll worth every penny


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## biggirafe (Jan 6, 2010)

GillRuss said:


> should there be a frame in the cut out to screw the light to ?



Can't say there should be as I'm not familiar with all makes, but mine and the caravans I have worked on have always had a wooden frame around the window cut out. 

Roof lights I believe do not always have a wooden frame as the rooflight provides its own strength and the cut out is much smaller. Having looked around the web at some pages it would seem that some do and some don't depending upon the make,

Sorry not much help I know


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## l77 tuf (Jan 7, 2010)

we fit a wodden frame inside for the screws to bite to and for strenght


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## Firefox (Jan 8, 2010)

I'm fitting a frame round mine. 25x32 timber battens jointed with right angle fixing brackets. My Fiamma Turbovent came without fixing screws. I  can't believe they were so cheap not to include them!


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## hogwillis (Feb 12, 2010)

*resealing hiki*



Firefox said:


> I need to seal the rooflight against the corrugated roof profile in a new build. Normally the Heki or Fiamma lights are sealed against a flat surface with a thin gasket and sika mastic. On my roof, the van has a 20mm corrugated profile in the steel for strength. So I need a foam rubber or hydrophilic gasket strip wich can be compressed to take up the 20mm difference in thicknesses, which will seal the rooflight against water ingress in combination with the mastic. Any ideas where to source such a sealing strip gasket product in the UK?



i usedto build these things so heres my tupenceworth
sicaflex 212 its in a tube like silicone.
you can get it in any large motor factors.
clean the area build up a leavel bed including the dips,
press the hiki into place,squeezing out the excess fix down the rooflight.if an unsightly amount has squeezed out spray with soapey water and scrap excess off gently. cure time 20 mins so dont stand admiring it til your finished
regards willis.


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## Firefox (Feb 12, 2010)

Thanks Willis. I've bought my Midi Heki now, just waiting fo the finer weather to fit it. I'll probably use a combination of your method, but I do have some old UPVC fascia board lying around and if I can find a suitable thickness to fill in the gaps I'll likely cut that to fit and Sika it in place beforehand to make a more level surface to work on.


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## hogwillis (Feb 12, 2010)

hi firefox
just make sure all gaps to the outside are covered with sicaflex because water will find a way.
any problems just shout.
good luk
willis


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