trialsrider Posted September 15, 2019 Share Posted September 15, 2019 I've just picked up my van which is going to be converted into a race van. It's a 2016 boxer x290 lwb. I've pulled out the old Ply lining and bulkhead as per the instructions of the converter. With race van conversions they usually expect a Ply floor to be left in. Mine was a 9mm plyfloor and terribly fitted so I've pulled it out, treated and filled all the holes and I'll use the old floor as a template and router a new thicker floor. I'm more than happy to do this as my build slot with the converter isn't till December as he is very busy. It will give me something to do and an excuse to not paint the house. But here is my dilemma. I'm 6ft 4 and really don't want to eat into my standing height in the van. With the 9mm floor I could pretty much stand up straight in the middle of the van. I've seen a lot of stuff on YouTube and people seem to put down a moisture membrane, then create a batton framework which they infill with insulation boards and then screw the plywood to the battons sandwiching the insulation. The total depth of the above is anything between 40 and 80mm depending on batton size. I'm definitely going to use a 12mm or 18mm ply floor but is insulation really that important? I'm not going to use the van in sub zero conditions. I'm also considering bonding the ply to floor of the van rather than screwing it but that would mean I couldn't fit a moisture membrane between ply and van floor. What are people's thoughts ? I did think maybe I could cut a duplicate 12mm floor. Cut sections out in it to create a frame / skeleton with which to fit 12mm celotex insulation boards within, bond frame and insulation boards to van floor, fit membrane on top and screw 12mm ply floor to frame. Thus creating insulation, moisture membrane and ply floor yet only 24mm depth. Any self builders who can offer advice ? Link to comment Share on other sites More sharing options...
Derek Uzzell Posted September 16, 2019 Share Posted September 16, 2019 Logically, your best bet would be to ask about this via the SBMCC https://sbmcc.co.uk/ though - as the end-product will be a ‘race van’ rather than a ‘motor caravan’, how well the floor is insulated may not matter so much. This link http://deepredmotorhome.com/insulation.php describes how an insulated floor was constructed and the thickness of the completed floor was about 40mm. No anti-moisture membrane appears to have been used. As headroom is important, I would have thought that just bonding thick plywood straight on to the Boxer’s metal floor would be OK and forget insulation and a membrane. This would potentially inhibit electrical cabling and/or heating ducting being run beneath the floor, but for comfort you could stick carpet tiles on top in the living area and use a sturdier material (rubber?) in the storage area. What does the converter advise? Link to comment Share on other sites More sharing options...
trialsrider Posted September 16, 2019 Author Share Posted September 16, 2019 Hi Derek Just spoke to converter. He is happy for ply floor to be bonded or screwed to van. Alturo safety floor vinyl is then bonded to the ply before wall and furniture construction. The garage floor and walls are chequer plate aluminium. Only the walls and ceiling will be insulated. I think I will go down the bonding route and opt for 18mm ply. It can just about be done with 3 8x4 sheets. One going transversely and the other two longitudinal. I was thinking bonding may actually achieve a more level floor as the ply can sit on a bed of adhesive on both the high and low corrugations of the van floor and this should reduce flex and creak. What adhesive should I use ? Is it worth treating the ply before it is put down ? I've read in a few posts on various sites marine ply is not worth the expense. But if I only need 3 sheets I feel it could be a good investment. QUOTE]Derek Uzzell - 2019-09-16 8:47 AM Logically, your best bet would be to ask about this via the SBMCC https://sbmcc.co.uk/ though - as the end-product will be a ‘race van’ rather than a ‘motor caravan’, how well the floor is insulated may not matter so much. This link http://deepredmotorhome.com/insulation.php describes how an insulated floor was constructed and the thickness of the completed floor was about 40mm. No anti-moisture membrane appears to have been used. As headroom is important, I would have thought that just bonding thick plywood straight on to the Boxer’s metal floor would be OK and forget insulation and a membrane. This would potentially inhibit electrical cabling and/or heating ducting being run beneath the floor, but for comfort you could stick carpet tiles on top in the living area and use a sturdier material (rubber?) in the storage area. What does the converter advise? Link to comment Share on other sites More sharing options...
John52 Posted September 16, 2019 Share Posted September 16, 2019 Heat rises so you aren't going to lose much through the floor. You will lose far more through cold bridges around the doors etc - so much so that some converters take the back doors out altogether and replace them with a coachbuilt like panel. OSB board is a good enough insulator for the floor - especially when you have foam based lino or carpet over it. Put your insulation higher up where it matters. I can recommend this https://www.harrisonstrimsupplies.co.uk/8m-x1m-FOIL-FOAM-VAN-INSULATION-WITH-PRE-GLUED-SOUNDPROOFING-THERMOLINER-SIMPLE Incidentally I took the lino up in my X2/50 because water had got underneath and the plywood was rotten. I feared the corrugated steel van floor would have rusted under the wet plywood. But the galvanising had kept it perfect - even where bare steel is exposed by self tappers going through the galvanising around it protects the exposed steel like the sacrificial anodes (lumps of zinc) bolted to the hull of a boat. Fiat van bodyshells are now outlasting Mercedes Link to comment Share on other sites More sharing options...
John52 Posted September 16, 2019 Share Posted September 16, 2019 trialsrider - 2019-09-16 10:26 AM marine ply is not worth the expense. Its not just the expense - its heavier so eats into your payload, and dense so it doesn't insulate so well. Link to comment Share on other sites More sharing options...
mikefitz Posted September 16, 2019 Share Posted September 16, 2019 Any damp proof membrane on the floor or walls in a panel van conversion may cause condensation within the void causing rot and mould. Having two vapour proof membranes, the van skin is the other, traps moisture. Mike Link to comment Share on other sites More sharing options...
Derek Uzzell Posted September 16, 2019 Share Posted September 16, 2019 trialsrider - 2019-09-16 10:26 AM Hi Derek Just spoke to converter. He is happy for ply floor to be bonded or screwed to van. Alturo safety floor vinyl is then bonded to the ply before wall and furniture construction. The garage floor and walls are chequer plate aluminium. Only the walls and ceiling will be insulated. I think I will go down the bonding route and opt for 18mm ply. It can just about be done with 3 8x4 sheets. One going transversely and the other two longitudinal. I was thinking bonding may actually achieve a more level floor as the ply can sit on a bed of adhesive on both the high and low corrugations of the van floor and this should reduce flex and creak. What adhesive should I use ? Is it worth treating the ply before it is put down ? I've read in a few posts on various sites marine ply is not worth the expense. But if I only need 3 sheets I feel it could be a good investment. SIKAFLEX 252 ashesive should do the job, but SOUDAL “FIX ALL FLEXI” gets good reports, is readily available and is siignificantly cheaper. I’d be wary of treating the plywood with anything that might inhibit adhesion of the wood’s underside to the van’s metal floor or the wood’s upper surface to the vinyl that the converter will be gluing to it. Consult the converter to avoid taking ‘good idea’ action that will impact negatively on what the converter subsequently does. Link to comment Share on other sites More sharing options...
John52 Posted September 16, 2019 Share Posted September 16, 2019 After seeing no rust on my X2/50 (galvanised) floor, despite wet plywood rotting on it and self tappers going through it for 10 years, I wouldn't bother gluing the OSB board down. Using 18mm OSB - so its thick enough to insulate, screw things down to, and not to warp, I would just put the odd self tapper along the edges to hold the edges down and stop it sliding - where the corrugations in the floor are high so it won't be standing in water at the bottom of the corrugation. Condensation or spills should drain out along the corrugations. If the OSB/plywood does get wet it will swell so you don't want a tight fit - leave a little gap around the edge so it doesn't bust the sides of the van apart. Good idea to treat at least the edges of the board in case it gets wet - just something to keep water out of the board, emulsion paint would do - then you avoid unpleasant paint fumes in the van. PS: Be very careful the floor and underside of the floorcovering is clean especially if you are sticking it down. Grit can stick to the underside of the floorcovering unnoticed when you roll it up. Nothing worse than finding a screw or lump of grit trapped under the lino so you've got to take it all up again to get the lump out :$ Link to comment Share on other sites More sharing options...
davidmac Posted September 16, 2019 Share Posted September 16, 2019 Hi, I would use 18mm spruce flooring plywood. It is 2.4 x 0.6 with a tongue on one side and end and groove on the other side and end. First cut to fit with the boards going across the van, working from front to back or back to front which ever is easier lay first board with a few blobs of adhesive here and there pva glue on the tongue and groove, repeat with all other boards. It's reasonably priced and with the tongue and groove no joints to move up and down. Will need weighting down while the adhesive sets. Regards David Link to comment Share on other sites More sharing options...
trialsrider Posted September 16, 2019 Author Share Posted September 16, 2019 davidmac - 2019-09-16 6:06 PM Hi, I would use 18mm spruce flooring plywood. It is 2.4 x 0.6 with a tongue on one side and end and groove on the other side and end. First cut to fit with the boards going across the van, working from front to back or back to front which ever is easier lay first board with a few blobs of adhesive here and there pva glue on the tongue and groove, repeat with all other boards. It's reasonably priced and with the tongue and groove no joints to move up and down. Will need weighting down while the adhesive sets. Regards David That sounds good Link to comment Share on other sites More sharing options...
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