5mm sheet/board for soffets

[Crofter]

The way I designed the fascias etc left me with only a 5mm depth for the soffets. Not ideal but it's done now. I used bog standard plywood which has mostly stood up ok, however at the corners of the building its possible for swirling winds to drive rain on to the soffets, and in these places the thin plywood is delaminating. My big worry is that starlings will find a way inside and create a noise problem- they were a real nuisance during the build.

 

What sort of materials should I be considering to replace the ply? I could obviously go with a better quality WBP or marine ply, but ideally I think a synthetic material that is zero maintenance would be better. I'm wondering about Foamex, or perhaps Dibond? 

[nod]

I’m not a big fan of plastic

But I used it anyway 

I used black grained UPVC Simply for maintenance 

The soffits where 5 or 6 mil from GAP 

In truth you can’t really see the grain from the ground 

But they are dull and could easily pass for painted 

[Russell griffiths]

6mm cement sheet, something from James hardy. I have used a smooth faced version before and it paints really well. 

 

[Crofter]

On 03/02/2020 at 07:23, Russell griffiths said:

6mm cement sheet, something from James hardy. I have used a smooth faced version before and it paints really well. 

 

 

Just getting back to this- looks like I may have some time on my hands this summer to do jobs like this... if I can get hold of the materials.

I can't find uPVC soffit boards any slimmer than 9mm so that's out, unless someone can point me to a source.

Cedral/Hardieplank cladding seems to be around 12mm.

 

@Russell griffiths did you just use tile backer board and then paint it? How has it stood up to exterior use? I imagine it would take a few coats, it must be quite thirsty?

 

I'm still tempted to use Foamex because it would be so easy to work with. It's supposed to be resistant to both water and UV for 7yrs... may be that's not long enough... and I'd worry that my preferred choice of slate blue would fade quite badly.

[Onoff]

You can get Aqua Panel in 6mm. That's got a smooth side and a "hairier" one. 

[tonyshouse]

I use wood, untreated and more robust 

[Crofter]

19 minutes ago, tonyshouse said:

I use wood, untreated and more robust 

The existing boards are wood and are not standing up well. Obviously at only 5mm I can't use any sort of solid board.

Maybe I could go for marine ply but tbh if I'm going through the hassle of replacing them I'd rather than choose something totally rot-proof.

[Cpd]

1 minute ago, Crofter said:

Maybe I could go for marine ply

Used this on an outside job and it’s also delaminating after about 5 years, not much but at the corners and will need replacing in the next year or two, I would go with something that is fit and forget. 

[dpmiller]

round these parts, thin cement board is the norm for developer soffits.

 

https://www.roofingsuperstore.co.uk/product/non-asbestos-undercloaking-strips-1200-x150-pack-of-10.html

 

https://www.samuelkirk.co.uk/non-asbestos-soffit-strip-2400-x-200-x-6mm-15271-p.asp

 

https://www.resistant.co.uk/products/multi-pro/

[A_L]

here is a another cement bonded particle board

 

 

building-board-product-and-application-selection-guide_2036226.pdf