Damp motorhome project - Roof repair

[Argar]

Hi Funsters,

Earlier this year we went into our 2007 Eura Mobile Integra (A class) to find the back of the motorhome damp with water dripping from the roof in the back. At this point, it didn't look too bad and we thought we'd caught it early enough. we did a temporary fix and tapped over the edge seals of the van and left a dehumidifier on inside. We left the van like this for a couple of weeks before making the decision to investigate further as the ceiling was getting softer.

Having removed the cupboards at the rear (nightmare job due to how the vans are built) and removing the ceiling boards we realised the extent of the damage. A number of the beams are rotten, the plywood on the top of the beams is delaminated over half the van. We'd got to the point of no return as we now couldn't take the van anywhere to be worked on so starts the job of repairing the damp.

Having read through various of the threads on the forums we like many others are now finding the more we strip out the worse it gets, water gets everywhere! We knew the van had a leak before we purchased it which had been professionally repaired (although we're now not sure of the quality of that repair!)

We've found the source of the leak is the seals around the top edge of the van most of which are degraded and split

At the moment, before the weather turns, the plan is to get the rotten beams of the roof replaced and then get new plywood on the roof. The roof is covered with tarpaulin to avoid any further damage.

We've managed to lift the roof for now allowing access to remove the plywood.

Help and support on how to proceed will be greatly appreciated.

 

[Argar]

Today's job will be to continue to clean up the ceiling ready to receive the new structure. I'll post some pictures later!

The ceiling and wallboards are no longer available so the plan is to recover some of the solid boards from the area and use these to replace the ceiling in the bathroom. As we've now lifted the roof we can access this and do the rebuild without removing any of the internal cupboards

As we plan to replace the topmost wood on the walls first it would be great to know what people suggest for wood to replace the beams and how to join these? Currently, all the wood is stapled which is expensive to do as DIY.

Also, what's the best adhesive to bond the wood to the GRP outerskin?

 

[Hagstrom]

Better informed people than I am will be along in a minute to offer expert advice but in the meantime, SIkaflex is King in the land of motorhomes and usually provides a permanent bond.

 

[Jamesh]

Sika Sikaflex EBT+ All-Weather Sealant White 300ml - Screwfix

Order online at Screwfix.com. High strength construction adhesive. Fast curing time with powerful initial grab. Multipurpose and permanently elastic. Also suitable for joint sealing and filling. FREE next day delivery available, free collection in 1 minute.

www.screwfix.com

I've used this stuff good stuff at a good price.

I'd pocket hole screw through to the remaining solid wood. You can get a cheap guide off eBay.

Cheers James

 

[Figaro]

I'm no expert either but after making sure the seals are now good, tanalised timber would be preferable, its injected to reduce risk of rot if it gets wet.
You could use recessed galvanised jointing plates for timber joints and sikaflex gor bonding.
Some of the threads on rot are quite informative if you do a search.
Good luck, it'll be worth the effort.

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[the1andonly]

The search box top rhs is your friend
Here's 2 to get you started

Dampness project - Floor now

Hi Funsters Following on from my previous damp project (https://www.motorhomefun.co.uk/forum/threads/dampness-project-roof-first.205004/) I am now about to resolve the floor dampness issues on our Bessacarr E795. I am reaching out to the wealth of knowledge in this forum and will again show...

www.motorhomefun.co.uk

Dampness project - Roof first

Hi Within this thread I will document what I find as our Bessacarr MH failed on a recent Hab check for dampness. The ceiling has started to go spongy after our first trip away. We purchased the MH around 6 weeks ago and the owner stated that the leak in the roof had been resolved as the ceiling...

www.motorhomefun.co.uk

Dampness project - Roof first

Hi Within this thread I will document what I find as our Bessacarr MH failed on a recent Hab check for dampness. The ceiling has started to go spongy after our first trip away. We purchased the MH around 6 weeks ago and the owner stated that the leak in the roof had been resolved as the ceiling...

www.motorhomefun.co.uk

 

[Jamesh]

When chasing damp around our previous caravan I found one of these was excellent at cutting out damp wood in the nooks and crannies of the van.

Broken Link Removed

Cheers James

 

[Argar]

When chasing damp around our previous caravan I found one of these was excellent at cutting out damp wood in the nooks and crannies of the van.

Broken Link Removed

Cheers James

Hi James - got myself a multi tool when I started looking - using it a lot already! Thanks

 

[Argar]

Figaro Tanalised timber does look the way to go - not as expensive as hardwood!

 

[Argar]

Thanks the1andonly I read the post by DJL220 last night and also the repair done by Kraken.

Did not remember seeing anything on joining wood to wood for the structural part (in place of the staples), will have another read later.

I know DJL220 did mention a contact adhesive for bonding polystyrene, would this also work for Celotex or Kingspan?

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[TheBig1]

I will update more tomorrow as I have a headache, but you need to glue timber joints with a urethane glue like gorilla glue and use a mechanical joint too. walls, insulation and wallboard or ceiling you need to use 2 part wallboard glue

Fine to use tanalised timber, but ensure it is dry before use, as it will shrink and could stain the wallboard

 

[James-Alex]

Best of luck with the project hope everything goes well

 

[MisterB]

Don't get overwhelmed by it all, slow and steady, glues and screws are your friends!!

 

[Argar]

I will update more tomorrow as I have a headache, but you need to glue timber joints with a urethane glue like gorilla glue and use a mechanical joint too. walls, insulation and wallboard or ceiling you need to use 2 part wallboard glue

Fine to use tanalised timber, but ensure it is dry before use, as it will shrink and could stain the wallboard

Thanks hope you feel better today.

 

[TheBig1]

Most of the parts you can source from O'learys https://www.olearymotorhomes.co.uk/shop-for-selfbuild-parts-1-c.asp

They sell the 2 part glue and the wallboard cheaper than anyone else I have found

The most important point to make about a big job like this is, don't panic or be daunted by the scale of the problem, attack it in smaller areas at a time. This is very important, as the more you strip out in one go the weaker the structure becomes. Take away the structural integrity and it will be hard to get back

Strip the first area about 1m squared approximately and clean up after every stage. Keep a record of how the fixtures and fittings come apart for reassembly. You will need sheet insulation, some people use polystyrene, but I much prefer to use urethane foam boards like cellotex or kingspan. spray foam to fill any awkward spaces. The already mentioned 2 part glue. Plenty of dried treated timber and a selection of tools to resize it and cut square joints. urethane glue for the wooden structure and stainless steel screws to avoid rust later

Make a plan to replace all rotten wood in as long a length as possible to help with structural strength. Build your new frame work and glue it and screw it together, then glue that to the outer skin holding it in place with temporary props till it sets. Cut the insulation to fit and test fit it all for one area first. When ready mix a quantity of 2 part adhesive and use this to glue the insulation in, filling gaps with expanding spray foam. Clean off any excess once the foam has fully set with a saw or knife to create a smooth surface. Then repeat the next section and once enough has been repaired to cover with a large sheet of board with suitable joints. Bond this onto the new frame and insulation with 2 part adhesive and again prop it till it sets using a thicker board to ensure it sets level without bulges

Basically that is the process of repairing a damp wall or ceiling, and pay extra attention to reinforcing the new frame around any windows, skylights or other openings. If you hit any snags or have questions, just ask away, as some of us have done a lot of these repairs over the years

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[Jamesh]

Also if you need to join two pieces of wood mid section, then your best to use a scalf joint of say 8x1 ratio the length being 8x the thickness of the timber being joined.

Cheers James

 

[Argar]

Jamesh thanks I'll look at scalf joints and see what I can find

 

[Argar]

James-Alex MisterB Thanks for that a depressing day today of finding more damp Can easily get overwhelmed by the work needed!

 

[Argar]

TheBig1 Thanks for that - some really useful information will look at that later a buy some of the required things. On the 2 part for the wallboards I think I read on the forum from Kraken that it wasn't possible to mix only part of the adhesive?

Can you confirm is this also used to bond the wooden structure to the GRP outer skin?

 

[Argar]

Continued to work on the rotten wood today. Thought I'd found the edge of the damp wood previously but found more damp on the ceiling in the bathroom. Interestingly the roof beam in this area wasn't reading as damp so surprised to see the wall beam below it is (picture below should help you picture this!)

The damp is reading as off-scale but the wood doesn't look to be rotten. Getting similarly high readings behind the shower but the wall board is still solid. What would people suggest doing with this part - continue to replace it or use a wood harder after having dried it?

The picture below shows the wall beam and roof beam (removed at this point) ceiling board was damp!

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[The Coops]

Start at the base and work your way up, it could be rising damp! If the readings are higher lower down it could be due to osmosis drawing water in , The practical solution and seeing how the van is under cover is to start at the bottom and work your way up, if you cure the roof you may find that everything south is also rotting , Not doom saying just be practical and logical
Tanalised dried wood , sikaflex sealant and waterproof wall board and patience!

 

[TheBig1]

you are using a very basic pin type meter for measuring damp. It will read the tiny amount of moisture from condensation on the surface of the wood. Pretty much useless for this type of job unfortunately. If the wood is solid, it will given the lack of further moisture dry out fine

2 part glue is not complicated, it requires so much catalyst for the given volume of base glue. Given experience and some basic measuring, you can quite easily mix 1/4 1/2 etc of the amount of glue. Weigh half the glue and weigh half the catalyst etc

back to the wood, a decent hardener will displace moisture, but can cause a change in the elasticity of the wood. Being a vehicle, it will move and flex on the road, so long timbers will bend with the vehicle. The hardener can stop this and the timber crack. so only use on timbers that are not likely to flex as part of the structure, like in the floor, just to be sure. This warning is just a worst case scenario of course. Soft wood is just rotten wood that has not disintegrated yet. If it feels wet and spongy, it needs replacing

 

[Terry]

Hi you have most information you need but I would use Puraflex 40 to glue/ seal things and if you have to join timbers use half inch ply cleats glued with Puraflex 40 and screws.It will also glue roof to timbers

 

[MisterB]

Scalf joints .... Now that's a piece of real joinery...... Though I think it's unlikely you would be able to do one without removing both pieces of wood making the joint and if you do then you might aswell just put a new piece of timber in the correct length !!

 

[2CVer]

Figaro Tanalised timber does look the way to go - not as expensive as hardwood!

The most rot resistant timber is a new product called Accoya. It is rated at 50 years outside weather resistance above ground and 30 years below ground. Here's a link. It's easy to work with and is readily available, but not many people have heard of it. More expensive than tanalised, but cheaper than hardwood and with a much longer life.

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[Puddleduck]

The most rot resistant timber is a new product called Accoya. It is rated at 50 years outside weather resistance above ground and 30 years below ground. Here's a link. It's easy to work with and is readily available, but not many people have heard of it. More expensive than tanalised, but cheaper than hardwood and with a much longer life.

Thanks for that - it might be an alternative to replacing our soffits and fascias at home rather than plastic.

 

[Argar]

TheBig1 Thanks for that - some really useful information will look at that later a buy some of the required things. On the 2 part for the wallboards I think I read on the forum from Kraken that it wasn't possible to mix only part of the adhesive?

Can you confirm is this also used to bond the wooden structure to the GRP outer skin?

Apologies Kraken quoted you on a few posts when it should have been The_Kraken.

 

[Argar]

Based on what TheBig1 said about the damp meter I suspect I need to invest in a better one (was considering this anyway as that one doesn't have a hold function so you struggle to read it).

Anybody any recommendations for what to use at the moment, read a few threads on here but struggling with links to ones on amazon and ebay no longer being available! Is a pinless worth the extra cost?

 

[Mark740]

With regards to bonding wood to wood, I used West System Epoxy(105). I used to slower hardener (206). You can buy a small kit, that should be plenty. Also grab some of the filler powder (406), this allows you to thicken to epoxy to make it easier to fill etc.

I bought the set of pumps that fix directly into the 105 and 206 bottles ( the numbers will become clear when you read about the system) 1 pump of each gives the correct mixture. I also got some plastic mixing cups, disposable small brushes and wooden spatulas ( Ebay and Amazon ). You will also want disposable gloves, a mask and plenty of blue roll.

The West System Epoxy is very easy to use, and I was shocked at just how strong it is. It is definitely stronger than the timber. However as mentioned above if you can create lap joints when cutting out your old timber then it will all help add strength.

<Broken link removed>

I got my stuff from the above place but on Ebay.

I also used a bit of polyurethane adhesive for replacing small areas of ply, it bonds very well to polystyrene and also foams up to fill gaps. Make sure you clamp etc as it will move the parts if you don't.

Most important thing is to find you leak/leaks. the water can track about a bit so have a good look around. also as said if the timber is just wet it will dry out fine. If it is rotted you will know, the multi-tool will removed the rotted stuff like it isn't even cutting.

I have not put all of my repairs into a write up yet but they are along the lines of Darrens (DL220). Take your time, drink lots of tea and i am sure you can crack it.

good luck

 

[Mark740]

Sorry for the poor structure and typos in the above post, I put it together whilst working on something....

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