replacing leaking rooflight

[number9]

I'm replacing an MPK 280x280 rooflight in my shower room in a Renault Master 2004.

 

The sealant/mastic tape looks as though it's seen better days and, because the rooflight is a few years old and looking a bit brittle, I've bought a replacement for 30-odd quid.

 

I'm getting confused by the number of different opinions - and youtube videos - on how to install this properly. It's a like-for-like replacement and so just needs 'sandwiched' over the existing hole by screwing together the top and bottom sections.

 

Some people say to infill the corrugated sections on the roof (roughly 7mm drop in height?) with plastic/Perspex, stuck in place with Sikaflex (or similar). Others say use butyl tape in layers - some use mastic (W4 or similar).

 

As far as sealant/adhesive goes, there's a wide range of opinion. Some saying Sikaflex/stixall do the job. Others saying these are too strong and will be very difficult to remove later. I do have some PU sealant from a motor factor that I've used to seal seitz windows on a previous van so this is another option.

 

Basically, I'd be grateful for clear advice on 1) dealing with the corrugated roof sections and 2) what sealants adhesives to use and how. Thanks. (?)

[blaven]

Please check your email?

[number9]

Thanks.

[Billggski]

Sikaflex is a brand name, and they make lots of different sealants.

Look on their website for the appropriate one.

https://www.sika.com/content/corp/main/en/solutions_products/industry-markets/marine-market/product-catalogue-marine/sikaflex.html

[mikefitz]

I have used this method with success.

 

Fill the corrugations with sections of window fitters cloaking profile,

 

https://www.wickes.co.uk/Wickes-PVCu-White-Cloaking-Profile-45-x-2500mm/p/162621

 

Bond in place with a general purpose PU adeshive sealant, example, PU 40 from toolstation,

 

https://www.toolstation.com/puraflex-40-high-modulus-pu-sealant-adhesive-300ml/p67949

 

Fit the rooflights on a generous bead of butyl sealent

 

https://www.sealantsonline.co.uk/Products/Butyl-mastic-sealants/EVE1387

 

Fit the hatch and clean up any excess sealant. Whitesprit is useful to clean up both types of sealant used.

 

 

After a few days clean any excess around the hatch flange and apply a thin bead of PU 40 over the joint to give a degree of protection to the mastic.

 

Using mastic as the main sealent allows for differential expansion and allows easy replacement in the future.

 

Mike

[number9]

thanks. really good guide. interesting you've suggested both pu40 for bonding then butyl for sealing. Most posts I've read just use one product. I have got something similar to PU40 (albeit in black).