Carport roof. Boiler condensation underneath. Treatment?

[Unklian]

Hi there.

I have a nicely constructed carport down the side of my house.
After being trouble free for 20+ years, the top has a couple of cracks
in the felt which I have filled with mastic.
I plan to have the roof boards and covering replaced this summer.

Following some building next door, I am having problems during very cold spells of condensation forming on the underside of my carport from their boiler exhaust.

Does anybody have a suggestion as to what I can treat the (New)
underside of the roofing boards with to prevent damage. ?
I will also be treating the timber structure with the same chemical.

I was thinking of spraying it with Creosote but......
There is twin & earth wiring for lights & sockets
under the carport which I probably can't avoid spraying.
(Does Creosote affect wiring insulation?)

The roof is currently tar-dipped chipboard which has absorbed the moisture slightly.
Would something like marine ply be a better start for the roof before I do anything to it?
Any suggestions for a treatment?

Cheers.

Ian.

 

[JohnD]

You are entitled to demand that your neighbour's flue gases do not cause a nuisance on your property. They can buy a flue extension that will blow it sideways, or take it upwards like a chimney. They are not especially expensive but have to be fitted by a qualified gas boiler person.

You could also fit a shield of something like transparent roofing sheets to keep the plume out

You can buy WBP ply which is resistant to water, and a far better material than chipboard. It will have to be felted as it is not available with a bitument coating. It might cost you about £25 per 8x4 sheet at Wickes (double at B&Q)

Treat the edges with paint or varnish as they are where any water damage will start.

 

[Unklian]

Thanks for that John.

WBP for a start then.

Then, I'm not sure what to do on top.

I'm looking into EPDM.

Need to find a quality fitter for North Sheffield.

Then I'll treat the underside.

The flue......Our two houses are side by side.
We both have boilers about 25 years old.
The carports (they have one) nearly meet in the middle.
We used to have a through draught from the rear of the houses to the front
so any damp blew away. Following the building of a downstairs toilet,
just next to their flue, the air is now very still so condensation forms.
......However......When their C/H man saw what was happening,
he is now removing the old boiler and installing a new combi boiler
upstairs in their old airing cupboard.

Hopefully, with my new roof and their new boiler, I should be OK.

Cheers.

Ian.

 

[JohnD]

it is much easier to treat timber after cutting and before fixing. Trying to treat the underside of a roof is very hard.

Lie the boards out, upside down, on a couple of dustbins and it's easy. You can turn them over to do the other side while the first coat soaks in.

 

[Unklian]

Update......

The neighbours' boiler is now moved and the underside
is drying off well.

With the aid of a friend, I have removed all the chippings from the top.
It turns out I needn't have been so worried, all seems fine.

When the weather improves, I am going to paint the top with a Bitumin solar reflective paint.

Here's the help I need now......Where the condensation was at it's worst, the
underside of one section of board was softened. The dark coating is easy to brush off with fingertips revealing the chipboard / sawdust underneath.
As this section is drying, small flakes are falling onto my car underneath.
Not loads, just an annoying little bit of "sawdust"

What is the best "treatment" to glue this back together?
(The overall board structure & strength is fine, just want to stop the dandruff!

PVA glue / water mix or can anybody think of something better?

Thanks.

Ian.

 

[JohnD]

The dark coating is easy to brush off with fingertips revealing the chipboard / sawdust underneath.
As this section is drying, small flakes are falling onto my car underneath.
Not loads, just an annoying little bit of "sawdust"

What is the best "treatment" ...

best treatment for chipboard is to put it on a bonfire and replace with ply.

 

[Unklian]

The dark coating is easy to brush off with fingertips revealing the chipboard / sawdust underneath.
As this section is drying, small flakes are falling onto my car underneath.
Not loads, just an annoying little bit of "sawdust"

What is the best "treatment" ...

best treatment for chipboard is to put it on a bonfire and replace with ply.

Yes, I know that to be the case as part of a full rebuild.

As I am having my drive block paved this year, I can't afford a full carport re-build too.

I'd just like to stop the flakes for a couple of years untill I can do the job properly.

Would the solar reflective paint that I am using on
the top surface be usefull? (I realise it is not sunny under the carport).

Ian

 

[Nige F]

Chipboard in any situation I just binned a load that formed a " built in bedroom unit" mould had got into the board ( before I bought the house ) and the stink from it was unbelievable In your scenario there will be a similar penetration of damp - I would think a paint would be no use - or indeed PVA - I suggest tacking a sheet of polythene over it to catch the loose bits until you re do it all