General Leaking roof vent

[Stephen217]

Hello, I have a 94 ducato Hymer camper and I noticed my roof vent over the table will leak slightly when it rains. I climbed up to the top and added another layer of caulking to the seal, but water still gets through. It seams that the water is not going into the ceiling but dripping down from the plastic housing itself. And the vent is in it’s closed position. Any advice on what the issue could be?

 

[theoneandonly]

Over time Vents Leak. Adding sealant typically will not work and total removal and fitting fresh sealant is required. Do not use a setting adhesive but a non setting sealant eg the W4 sealant strip.
some info i've previously compiled
Window Rooflight Sealant (for removable/replacment items with mechanical restraint)
Hodgson SEAMSEAL CV (for Metal Surfaces)
Hodgson SEAMSEAL BR (for Plastic Surfaces)
Non-setting synthetic rubber bedding sealant for metal joints.
Does not skin. The surface of the sealant will appear dry to the touch after several days but will remain pliable beneath the surface. Working time: Approximately 20 minutes.
Primers are not normally required for good adhesion to most metals. Mould resistance: Good
Seamseal CV is a non-drying bedding sealant as described in the National Caravan Council Joint Sealing Manual.

Caravax Caraseal IDL99
Non-setting bedding sealant

W4
W4 Mastic Sealing Strip is formulated for the sealing and re-bedding of caravan and trailer tent fittings.

 

[Ronnie63]

Oh dear! I replaced our heiki frame due to a leak but used sikaflex to seal it! And even worse that was not the culprit of the leak! It was pock holes in the aluminium roof skin.

Is this going to come back and bite me?

Thanks Ronnie

 

[BurntMarmite]

The internet is full of experts throwing sikaflex about - even one of my friends who watches yt experts has just done the same, I've given up answering and advising.

Sikaflex will work a treat and hold the skylight in place and seal. For a brief period. It is non flexing so over time, van movement, expansion etc will cause it to separate/crack and water will get in. It also may not stick to unprepared surfaces. There may be a specific "model" of sikaflex that will work , but no one mentions that.

Others use silicone and say its fine. Again, it is for a brief period.

As above, non setting flexible mastick is the way to go - caraseal is OK as above - but I prefer Dekaseal 8936 (google it) - its a non setting dab off sealant - less messy than caraseal but same principle.

But as above skylights will leak its just a matter of when. 1 yr? 5? 10? who knows lol. But its not a big job to reseal if you use non setting stuff - but good luck getting a PU adeshive off the roof! (I had a pro converson who used non setting on 2 skylights, and sikaflex on the 3rd - don't ask why - but that leaked and it took hours to remove it from the roof and took off most of the paint..... We had words.....)

 

[Ronnie63]

I thought I had done my homework on this, clearly not! it's suppose to be flexible, but I guess if the bond comes undone it will leak! I did prep the area well and it was a brand new heiki frame also prepped and sanded slightly, fingers crossed it stays sealed.

The bigger problem is the roof skin! the whole flat area of the roof has been painted with a rubber type white paint and I can see dollops of sealant allover the roof! It looks like the skin has corroded from the inside out where it lays flat on plywood, I will have to clean and apply some more of this rubber paint come warmer weather but for now it's watertight.

Thanks Ronnie

 

[theoneandonly]

The other favorite ask is what do i use to stick down a solar panel , There a several Sikaflex products for Motorhome use . the most important part of the selection is what am i sticking to what, what pretreatment is required what cleaning just IPA or removal of releasing agents from new plastic parts Sika activators for specific products. SIkaflex branded products are expensive and will do the job designed for if you select the correct one and treat as required. I know someone who extols the virtues of 291 a marine grade product with particular requirements to stick down Aluminium brackets (to fix to solar panels) on the same roof construction as mine , £15 a tube i use Puraflex40 (toolstation £5 , parent company Sika ) similar tensile strength. does the job. The data sheet is your friend. Or contact Sika by email they will advise, but give them all the details.

 

[BurntMarmite]

The other favorite ask is what do i use to stick down a solar panel , There a several Sikaflex products for Motorhome use . the most important part of the selection is what am i sticking to what, what pretreatment is required what cleaning just IPA or removal of releasing agents from new plastic parts Sika activators for specific products. SIkaflex branded products are expensive and will do the job designed for if you select the correct one and treat as required. I know someone who extols the virtues of 291 a marine grade product with particular requirements to stick down Aluminium brackets (to fix to solar panels) on the same roof construction as mine , £15 a tube i use Puraflex40 (toolstation £5 , parent company Sika ) similar tensile strength. does the job. The data sheet is your friend. Or contact Sika by email they will advise, but give them all the details.

Sika advise not to use their product for sticking down panels (I've seen an email from them on another forum)
The problem isn't Sika is naff - the problem is the paint (on sevel vans) comes off! So the sika is great - it sticks to the brackets and paint, but the paint does not stick to the metal roof (assuming panel van).
Quite a few photos showing that.....

(I have to say, I used stixall on last van, but it was nissan and the surface area was *huge*. I'd not use glue on a fiat)

 

[theoneandonly]

Sika advise not to use their product for sticking down panels (I've seen an email from them on another forum)
The problem isn't Sika is naff - the problem is the paint (on sevel vans) comes off! So the sika is great - it sticks to the brackets and paint, but the paint does not stick to the metal roof (assuming panel van).
Quite a few photos showing that.....

(I have to say, I used stixall on last van, but it was nissan and the surface area was *huge*. I'd not use glue on a fiat)

Sorry to confuse any one, i was thinking about "White box " motorhomes particularly (like mine). Sticking panels to a sevel van (PVC) tends to cause convusions with extra screws/ bolts through roof or fit to a roof rack being concidered the safest/ best option. the option of removing the paint first tends to be ignored.