I have just started a Swift Silhouette renovation, approx 1985 and damp.
I want to increase the insulation substantially, from 20mm mostly expanded polystyrene to 40-50mm extruded polystyrene I think on the ceiling and walls.
Question, I think I should strengthen the timber frame, not least to increase the depth of the wood enclosing the insulation. What is the best way to do this. I see a few options (willing to do this thoroughly, have already stripped back to frame and alu),
With regard to the ceiling,
1. Replace cross struts one by one with new wood through the original centre wood (which is undamaged). Possibly in different locations down the length for simplicity.
2. Screw on additional wood to the existing wood - down the centre, this is an option for the cross struts as well.
I can't see a viable way to replace the centre wood, it is sound, I don't think I want the whole roof off.
There is substantial water ingress but no rot except in low areas, I think I will work down, so the first main exterior job is to replace the mastic down the centre rail on the roof, use duct tape as a short term stopgap.
You appear to doubling the thickness of the timber throughout the whole van to accept the additional insulation thickness. This will also double the weight of the framing. You will have to have a go at calculating what the increase will be and deduct it from the specified payload, to see if what remains will be sufficient.
This will also result in a lot adjustment to the furniture. No wish to offend, but is all this work worth it on a van of this age?
and by the way the post is reading it seems to suggest that you have already removed all the furniture? the furniture form part of the strength of the caravan and in doing so the walls would have warped
Thanks for responses, marg6 and chrisn7.
Yes, I am not sure I want to double the weight of the frame.
I am indeed planning a lot of work, and I intend to do the required calculations and adjustments to loading etc. I have removed all the furniture with the intent of rebuilding (differently) once the damage is repaired. Not tackled a caravan before but I do have quite a bit of building experience, and am up for a challenge. I am sure the walls are not warped, it is pretty solid despite some damaged framework. I am doing a blog here, http://sarahsretrocaravan.blogspot.co.uk/
well seeing as you have removed all the furniture then you might aswelll scrap the van! the only thing that stops the sides and roof from moving was that furniture
I am hardly the first person to strip back a caravan, as long as I am careful it can be rebuilt.
BTW I have decided to replace the cross struts with taller narrower wood, it is only about 25% heavier. The extra insulation will add less than 5 kilos in total.
Yes, replace rotted timber in sections. Do front end first & so on & then it will not go out of line. Use polyurethane sealant/adhesive to stick it down & seal outside as well. Brand names are Sikaflex 512, Tigerseal, PU18 etc. Search Amazon for it. It's the only sealant you should use. Silicone is not up to the job. This website should point you in the right direction. Don't be afraid to post for more advice. Plenty on here do know what they are talking about.
Thanks Opensauce,
That matches how I am thinking. I have got about half way down one side. I hope its OK to do one side at a time (the one I am working on is the only one with obvious damage). So far so good, I am surprised how robust the whole roof is, considering the obvious damage.
I have some Sikaflex, ready to go - relying on duct tape and tarpaulin for now.
Next question, does anyone have experience with Liquid Roof? - it's basically rubber. The pictures look good, but is more common in the US I think.
Rubber may be effective, but its heavy stuff. Washers and seals seem light enough but sheets of it are heavy. It would also be high up, which is the last place you want extra weight
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Topic: Renovation while improving insulation
