Mastic advice please

[everhopeful]

I need to touch up existing mastic around things like roof joints, roof-lights etc.

 

I can't buy caravan mastic locally and am wondering about the merits or otherwise of domestic external mastic.

 

Products like Unibond external silicone are not cheap, but are they really much different from "proper" caravan mastics?

 

If I do need proper caravan mastic can anyone recommend a flexible and easty to apply product?

[Keithl]

Hi Everhopeful,

 

I wouldn't use domestic sealant on my MH as it isn't designed for the movement and flexing a MH body gets.

Have a look at the Butyl sealants that CAK Tanks sell. I've used it to fit a blanking plate in place of the Status aerial and found it good to use. All you'll need is an ordinary sealant gun to take the cartridge.

 

Keith.

[George Collings]

If the problem is only cosmetic as the sealants have become dirty its amazing how well they clean up with the aid of a small stiff brush and some household detergent. If the gaps are really small an old toothbrush may do the trick.

 

Due to the dirt anything you put on top will not bond to the old sealant . Avoid silicon products as far as possible as if they do fail the traces of silicon left behind stop most other sealants adhering properly.

[Guest 1footinthegrave]

Only one for me is Sikaflex 512, not cheap, but good stuff rarely is.Not a problem to order and buy online.

 

I have recently done a similar exercise, both internally and externally. My advice would be to prepare all the joints to be re-sealed first by removing any loose / perished stuff, clean with methylated spirits, then use masking tape to get a neat finish. The sealant will keep in the tube once opened ( but not indefinitely ) provided you exclude air from it, and use a new nozzle for re-use, but my advice would be to pick a good dry day and do it all in one go. ;-)

[flicka]

Sikaflex 512 caravan motorhome trailer adhesive sealant system - 300ml tube, white

 

A unique all purpose adhesive and sealant, designed for the build and repair of Caravans, Motorhomes and Trailers.

 

A professional grade, one part polyurethane hybrid that can be used externally and internally and bonds and seals in one operation.

 

•UV resistant, colour stable will not case staining and resistant to ageing and weathering.

 

- Try this site.

http://www.magnummotorhomes.co.uk/view_product.asp?productID=125&catID=45&subcatID=

[Guest 1footinthegrave]

??????????????? or Google search Sikaflex 512 8-)

[everhopeful]

Thanks all for such excellent advice.

 

I was looking at alternatives to caravan products because I was hoping to do the job this weekend. However, after your commments on silicone mastics I'm going to delay the job until I've ordered the proper stuff on the net. Looks like Sikaflex 512 wins the vote so I'll go for that.

 

On the bright side, if I can get some this week I'll be able to do the job on royal wedding day! Bliss... :D

[Guest 1footinthegrave]

One final thought, ensure your skeleton gun is of good quality, Sikaflex takes some pushing through,helps if you put it in a warmish place before you start, my brand new gun just broke in my hand after just a few squeezes, I had to make a quick dash to a couple of builders merchants to find a better quality gun. Keep your bead size quite small by just nipping off the end of the nozzle, good luck. ;-)

[thebishbus]

Hi. If you are still looking for a good and possible cheaper alternative, I would recommend , " Everbuild Stixall ".I used to use Silkaflex, but now use "Stixall " instead, even works in the rain or under water. 8-)

Brian B.

PS " Stixall " is available from builders merchants.

[weldted]

Caraflex is a non setting mastic which will skin over used for installing roof vents, door frames etc, aids removal if you need to and will flex a bit helpful to absob any movement in extreme temperature. Sikaflex is a great adhesive but if you should ever have to replace say a roof vent you can remove Caraflex easier and it is only around £4.00 a tube!!

[njw]

I agree with weldted ,sikaflex is goodand is ok on solar panels and satellite equipment , but having spoken to russell from o,learys he recommened the none setting adhesive for fixing roof vents, heki etc he could have sold me sikaflex at twice the price so as they build motorhomes i went wtih his choice

[everhopeful]

OH, the plot thickens!

I've now been surfing around and it seems to boil down to the two main products mentioned here; Sikaflex and Caraflex. There are others as mentioned in this thread, but having no experience with caravan mastics, I think I'd better steer towards the mainline products.

 

Sikaflex 512 is a professional sealant / adhesive that needs skill to apply properly, but is so strong that removal at a later date will be nigh on impossible.

 

Caraflex IDL99 is easy to apply, but, though not as strong, can be removed if necessary at a later date. It doesn't actually set and remains sticky. I'm assuming it skins over though, or everything would stick to it!

 

I'm thinking my solution might even be to try both. Postage costs would likely be the same for two items anyway.

 

Thanks again for your responses to this sticky problem. (sorry)

 

 

[Keithl]

Everhopeful,

 

Please don't rule out the SIKALASTOMER BUTYL SEALANT from CAK Tanks that I mentioned in my first post. It is from the same manufacturer as Sikaflex 512.

 

Here is the quote from their brochure

"Sikalastomer 710 butyl sealant is a high quality

non setting sealant used for a variety of joints

in caravans and motorhomes. It is especially

suitable for those situations where there is the

possibility of future disassembly, such as edge

trim on motorhomes, caravans and boats,

windows, rooflights and airvents etc. Due to its

very sticky non-setting flexibility it is ideal for

re-sealing of edge trims that have been sealed

with ordinary non-setting mastics which dry

out. Available in black, grey & white, size

300ml cartridge".

 

I have used this product and can assure you it does exactly what it says. Why pay for two when one will do the job properly?

 

Keith.

[Guest 1footinthegrave]

It's a nightmare isn't it differing opinions,but I used a "premium" non setting mastic on my Heki rooflight, during hot weather down in the south of France I noticed it was oozing out and causing the acrylic dome to stick on it, kept removing it, it kept creeping out. Finally scraped the majority out when we got back and sealed it with Sikaflex, I guess you have to take everyones input and make your own judgement, i.e what's the likelihood you will ever need to remove what you are attempting to seal, keeping moisture out is my top priority and so far sikamalarky seems to be doing that. Also I have yet to find anything that won't yeild to a sharp stanley blade should it need removal in the future, good luck whatever you choose. ;-)

[Guest 1footinthegrave]

It's a nightmare isn't it differing opinions,but I used a "premium" non setting mastic on my Heki rooflight, during hot weather down in the south of France I noticed it was oozing out and causing the acrylic dome to stick on it, kept removing it, it kept creeping out. Finally scraped the majority out when we got back and sealed it with Sikaflex, I guess you have to take everyones input and make your own judgement, i.e what's the likelihood you will ever need to remove what you are attempting to seal, keeping moisture out is my top priority and so far sikamalarky seems to be doing that, no doubt other products recommended by other forum members do a similar job. As for removing Sikaflex I have yet to find anything that won't yeild to a sharp stanley blade should it need removal in the future, good luck whatever you choose. ;-)