Soft wood under Hymer garage floor

[Robert Harkness]

Hi, has anyone encountered rot under a Hymer garage floor? If so, how did you deal with it, or who did you entrust with the repair?

Thanks in hope and anticipation.

Rob

 

[pandas]

What model/year and specifically where? And where do you think it's coming from? And what part of the country are you in?

 

[scotjimland]

Hi Rob.. I had rotten wood, behind the rear wheel, underside of the garage floor of my 2001 Hymer B644 .. I repaired it myself..

depending on how advanced it is it is a doable DIY job..

full thread here on how I repaired it.. https://www.motorhomefun.co.uk/foru...mer-under-garage-floor-at-rear-corner.130639/

 

[CazPaul]

Its a big problem on some vans, 1997 -2006 are the worst affected I have found.

They should have used GRP to start with.

It was meant to be an area where owners checked every year and made good any rot etc.

In reality 99% of owners never touched or even looked at the area, out of sight out of mind.

I have found the models with transverse bed over large garage are the worst affected, seem to be more exposed than the models with the habitation door at the rear, ie 640 Starline.

It then depended on where the van was stored(damp, windy climate), if it was driven regularly in driving rain, whether it had mud flaps as they offer some protection.

I have put my fingers through quite a lot, the rot has been extensive, some even stick a strip/area of wood on top to try and cover it up(bodge job).

If it gets extensive it can even extend to the area coming up the sidewall(below the garage skirt) and also at the rear area. I have seen areas of garage floors collapse when it gets bad.

Don't ignore it or cover it up.

 

[klaatu]

I discovered it on my 1999 B534 just recently, and found the thread by @scotjimland as above, and repaired it in exactly the same way with the same products. And I'll take this opportunity to say thanks to Jim for posting about it.

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[Robert Harkness]

Hi, Scotjimland
Thank you for that information. I looked at the thread, and there are a few helpful suggestions. Can you add anything, like a step by step of what you did? Sorry to be dense, but the thought of tackling the job is a bit daunting.

 

[Robert Harkness]

Hi, Pandas

It's a B644 as per Scotjimland's post, in exactly the same location - under the garage floor - and we are currently in the Oxford area.

 

[scotjimland]

Hi, Scotjimland
Thank you for that information. I looked at the thread, and there are a few helpful suggestions. Can you add anything, like a step by step of what you did? Sorry to be dense, but the thought of tackling the job is a bit daunting.

Hi .. it's daunting but not that difficult.. provided the rot hasn't penetrated too deep or too wide an area.. mine was about 9 x 12inches and about half the depth of the plywood..

first thing I did was dig out as much of the soft wood as possible.. using a sharp wood chisel.. was quite ruthless.. then dried it using a hot air gun.. it's important to get it as dry as possible.



then applied two coats of Ronseal Wood rot hardener.. let that dry until it was hard

next day I filled with the Ronseal two part epoxy wood filler.. you have to work quickly, it 'goes off' quite quick.. like fibre glass resin does.



when that was hard I sanded it down, then then painted Hammerite underbody sealer.. two coats ..



hope that helps.. any other questions just ask..

 

[Robert Harkness]

Hi Scotjimland,
Sorry, just realised there is another page to the thread - I'll go and read that!!

 

[scotjimland]

Hi Scotjimland,
Sorry, just realised there is another page to the thread - I'll go and read that!!

no worries.. I've just done it

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[Chris]

I thought German vans didn’t leak like sieves

 

[scotjimland]

I thought German vans didn’t leak like sieves

water damage on the underside of the floor, they said it was due to salt on UK roads.. which they don't use in Germany ..

they now use GRP for the floors .. sorted ..

 

[Chris]

water damage on the underside of the floor, they said it was due to salt on UK roads.. which they don't use in Germany ..

they now use GRP for the floors .. sorted ..

Germans are liars Jim.

They also said they wouldn’t invade Poland if you remember

 

[scotjimland]

@Robert Harkness

looks like you ran out of free posts..

the forum is a wealth of useful (and sometimes useless) knowledge

the £15 subs would be worth it ..

in any case good luck with the repair..

 

[scotjimland]

Germans are liars Jim.

They also said they wouldn’t invade Poland if you remember

how can you say that..

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[Garfields]

O yes they do ( use salt that is)

 

[pelican]

water damage on the underside of the floor, they said it was due to salt on UK roads.. which they don't use in Germany ..

they now use GRP for the floors .. sorted ..

Strange thing to say not using salt on roads

 

[Northernraider]

I found one very small soft patch on the underside floor on my hymer.
Strange thing is it isn't near the wheels it's at the very back outer corner.
I scraped out the soft bit , filled it and have painted the underside floor with hammerite.
It's gloss so the water doesn't penetrate it now. The rest of the floor is solid but I'll keep an eye on it. I had considered covering it with a thin sheet of plastic but I think the paint should do it.

 

[Allanm]

Strange thing to say not using salt on roads

Didn’t realise salt rotted wood.......

 

[Northernraider]

Didn’t realise salt rotted wood.......

Yep it does ..That's why they tell you not to use salt or calcium chloride on decking etc

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[CazPaul]

I found one very small soft patch on the underside floor on my hymer.
Strange thing is it isn't near the wheels it's at the very back outer corner.
I scraped out the soft bit , filled it and have painted the underside floor with hammerite.
It's gloss so the water doesn't penetrate it now. The rest of the floor is solid but I'll keep an eye on it. I had considered covering it with a thin sheet of plastic but I think the paint should do it.

Not sure about plastic Tam, that's what Swift used to do and it was a disaster I recall, timber needs to dry out and breathe.

 

[scotjimland]

O yes they do ( use salt that is)

Strange thing to say not using salt on roads

I think you both missed the emoji wink ..

which they don't use in Germany ..

 

[scotjimland]

Not sure about plastic Tam, that's what Swift used to do and it was a disaster I recall, timber needs to dry out and breathe.

Just my understanding, not a timber expert..

the floor is made of plywood.. it doesn't need to "breathe" like natural timber.. it should be stable and not expand, contract or warp but requires sealing to prevent water ingress and rot .. clearly the Hymer under-seal that was applied didn't do the job of protecting from salty road spray ..

 

[Northernraider]

Not sure about plastic Tam, that's what Swift used to do and it was a disaster I recall, timber needs to dry out and breathe.

Aye in the end I didn't do it Paul but I thought long term it might have stopped any further damage. But to be fair the van is 14 years old and I found one small patch approx 4 inch square that was a little soft on the underside.
So wasn't a big drama.
Painted the underfloor on both sides of the van from rear wheels to towbar and I'll keep an eye on it

 

[jdk62]

Germans are liars Jim.

They also said they wouldn’t invade Poland if you remember

Emissions scandal.... Enough said....

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[CazPaul]

Just my understanding, not a timber expert..

the floor is made of plywood.. it doesn't need to "breathe" like natural timber.. it should be stable and not expand, contract or warp but requires sealing to prevent water ingress and rot .. clearly the Hymer under-seal that was applied didn't do the job of protecting from salty road spray ..

Not sure about that at all, once moisture gets in anything containing timber, the moisture needs to get out, which is prevented by the black underseal. It's a difficult one Jim I have heard points for and against what to do for the best.

 

[scotjimland]

Not sure about that at all, once moisture gets in anything containing timber, the moisture needs to get out, which is prevented by the black underseal. It's a difficult one Jim I have heard points for and against what to do for the best.

yes, I agree..

best course of action would be to cut out and replace.. but that's a big job.. the repair I did should be good for years ..

it's like filling a car .. best would be a new panel.

 

[Northernraider]

Not sure about that at all, once moisture gets in anything containing timber, the moisture needs to get out, which is prevented by the black underseal. It's a difficult one Jim I have heard points for and against what to do for the best.

I think if you dry it out first and then seal it there shouldn't be any moisture in the wood.

It's certainly covered on the inner side as mine has laminate inside the garage same as the internal floor.

By the looks of mine it actually looked a little burnt like someone had tried to dry the patch out with a blow torch or something.

 

[BusyBuilder]

Good set of mud flaps work wonders. Mine, Fiat Maxi chassis Hymer B544 has lorry type flaps fitted, the van is 6 years old and looks as good as new underneath.
Gloss oil based paint is not the best to use as it will hold any damp in, not letting it out and eventually breaking down. A very good quality water based paint is far superior to oil based gloss.

This

https://www.rawlinspaints.com/home/...ood-finishes/1396-jotun-butinox-futura-3.html

is by far, a very good paint finish, 2 or 3 coats will last a lot longer than any oil based paint. I painted my timber garage door 8 years ago,and it's still in good condition despite not having been touched since.