Over cladding a barn. Viable or stupid idea?

[AJB Temple]

My house is a bundle of barns. The main one is a 16th century (somewhat hacked about by an *****) frame, clad in black painted pine feather-board. Luckily the main barn is not listed.

The feather-board needs a good deal of repair, all window surrounds need replacing, and the whole lot needs repainting. I can easily spend £3000 on repainting, for good quality materials, scaffolding and repairs. And in 10 years or less it will need doing again.

My idea on which I am seeking advice:

Remove any rot, patch and seal, then batten the whole barn with oak battens over the existing black cladding, and re-clad with top quality oak feather edge, either left natural or sprayed with preservative.

I realise that this will add 2 inches of thickness all over, and obviously I could rip off the old cladding, but I am thinking from an insulation point of view, and saving time, and avoiding disposal of materials, why not just re-skin the building in oak?

I should add that I have an almost limitless (for me) supply of oak at my disposal. I had dozens of trees from a storm years ago. I sold a lot of it but I still have a great deal left and I can easily get a local yard to machine it for me into boards of whatever width I want up to about 14".

I am thinking I could tack a membrane over the existing cladding, and just cover the whole lot.

For an idea of scale, the main barn is roughly 40 metres long and 10 metres wide. apart from a projecting music room that was added, it is a simple rectangle.

Any thoughts?

AJ

 

[AJB Temple]

By the way, roof overhang is not an issue. The roof is very steeply pitched and overhangs by 16 inches, plus gutters. I will be replacing all guttering with copper or galvanised anyway.

 

[topchippytom]

A lot will depend on any planning issues that may be need to be applied,From an insulation point of view it makes sense but how much rot is in it at the moment as could well affect any new timber,As for getting a local firm to mill the oak,why not just pick up a new woodlands mill for 3/4 k and mill all your own stuff as i do.

 

[Rorschach]

As long as you have a nice secure substrate to fix the new cladding to I would say go for it.

 

[MikeG.]

Strictly this would require planning permission, and if you are in a conservation area or within cooee of a listed building then the listed buildings people will get interested too. Oak boards can be problematic as a cladding. I've seen them cup so violently that they pulled all the screws out of the battens. Obviously that's all about having the outside dry at a different rate to the inside, and without paint, I really don't know how you'd ever get over that issue. The other big deal for me is the nasty detail you'd leave at the bottom edge, where your cladding would hang a long way out over your plinth.

It's doable, Rorschach, but there are significant challenges. In your situation, it isn't something I would be doing.

 

[RichardG]

I would also take advice on the fire implications, that’s a very thick combustible cladding you would then have...

 

[Jacob]

Replace all cladding with western red cedar. Won't need painting, treating, anything in terms of maintenance.
Or corrugated iron - easy to paint, every 10 years or so.
I would not paint any large areas black - this makes for high temperature stresses etc etc. If you must paint then white is best.

 

[RobinBHM]

Replace all cladding with western red cedar. Won't need painting, treating, anything in terms of maintenance

I think this is a wind up.

Good one

 

[Jacob]

Replace all cladding with western red cedar. Won't need painting, treating, anything in terms of maintenance

I think this is a wind up.

Good one

Lifespan of 50 -100 years and longer, used for roofing shingles, much more durable than oak.
https://russwood.co.uk/exteriors/claddi ... red-cedar/

 

[MikeG.]

.......I would not paint any large areas black - this makes for high temperature stresses etc etc. If you must paint then white is best.

Every barn in East Anglia is painted black. I would suggest following the local vernacular.

 

[Jacob]

.......I would not paint any large areas black - this makes for high temperature stresses etc etc. If you must paint then white is best.

Every barn in East Anglia is painted black. I would suggest following the local vernacular.

Would have been creosote I guess - much better than modern paint, though you wouldn't want it on a house - smelly and toxic.

 

[rafezetter]

Replace all cladding with western red cedar. Won't need painting, treating, anything in terms of maintenance.
Or corrugated iron - easy to paint, every 10 years or so.
I would not paint any large areas black - this makes for high temperature stresses etc etc. If you must paint then white is best.

Problem with painting it white is that's not historically the right colour, and might even cause issue on it's own, some people are right twitchy about that, and not just officials either, an annoyed local could still drop you in it with an official complaint.

While the idea seems good with the unlimited oak availability there's a reason why so many barn conversions over the years have been stripped back to the frame, well insulated and then clad with metal.

There is also the issue of what happens when it comes time to sell the property - what's your timeframe for that?

Doing something more costly now, but "futureproofing"; as building standards for insulation and thermal efficiency are only ever going to become more stringent as the costs of energy rise, could be a possibility worth looking into.

There are also methods of making exterior metal cladding as a heatsink work for you as an energy source, but that's right up there alongside more experimental practices, and obviously in the UK, less efficient year round.

Budget permitting, you may be able to do as some barns have and strip back, insulate etc as before, but then still semi clad in wood to ease the harshness of the modern cladding. I'm sure I don't have to remind the assembled readers that narrow(ish), thinner strips of Oak will behave a lot better year round compared to full planks.

A much as I'd love a barn converstion home, I don't envy you the upcoming choices (or cost), 3k every 10 years or less or a one off cost that's significantly higher.

 

[rafezetter]

.......I would not paint any large areas black - this makes for high temperature stresses etc etc. If you must paint then white is best.

Every barn in East Anglia is painted black. I would suggest following the local vernacular.

Would have been creosote I guess - much better than modern paint, though you wouldn't want it on a house - smelly and toxic.

There's Sho Sugi Ban - used for centuries in Japan, whom I beleive have a wider range of weather than the UK, historically cedar, but not always where Cedar isn't as common, I'm sure Oak could also be treated the same way.

It's becoming more common in the UK these last 5 years or so, so there's a case to be made for that as well.

 

[meccarroll]

This is interesting, you have mountains of oak to use, very lucky. Although Jacob is right is saying Cedar would be an excellent material to use Oak is not at all bad either if it's freely available. I'd calculate the cost of slabbing the oak trees, storing them while they dry and then milling too. While oak is very durable it is also corrosive to normal fixings so consider marine grade fixings (stainless steel) even stainless steel has grades so make sure you obtain the correct grade for external use.

Stripping off the old cladding might seem a pain but in my experience it would not take long and there are always plenty of people looking for free firewood (you just need to advertise a bit). If you are going to do this amount of work then why not do it right from the start and see what's under the decaying cladding? A vapour barrier goes on the inside of a building so you should be looking at a breathable membrane between the the main frame and any battens on the outside of the external leaf (external walls).

Adding insulation can help cut down heating bills but unless calculated and done properly can also cause problems in old buildings (interstitial condensation) the entire internal to external wall should be looked at if you do consider adding insulation so "maybe just clad".

If it was me I'd be thinking of chatting with planning and building control, slabbing the timber and drying for a year hand a half them milling the timber and planning the replacement in stages. You will probably need scaffolding to do this work and if you do it in stages you could buy enough to move it along with each phase then sell it off when you have finished (probably get your money back too).

Just my thoughts.

 

[Just4Fun]

I can easily spend £3000 on repainting

Your place is 40mx10m. Ours is 30mx9m. I don't recall the exact figure but it definitely cost us rather more than £3000 to have it painted. (We didn't do the painting ourselves).

why not just re-skin the building in oak?

Our walls are solid timber logs clad outside with pine boards. When repairing a small area (the outside of one room) we added new cladding over the top of the existing. We did this to avoid the work of removing the old cladding and also thought it might add something to the insulation. That hasn't caused any problems so if I were faced with the same choice again I would over-clad rather than ripping off the existing cladding. I can't comment on the choice of oak as the cladding material.

 

[MikeG.]

I can easily spend £3000 on repainting

Your place is 40mx10m. Ours is 30mx9m. I don't recall the exact figure but it definitely cost us rather more than £3000 to have it painted. (We didn't do the painting ourselves)........

I lived next door to a barn until 5 years ago. I organised the painter for the barn owner last time it was painted (6 or 7 years ago), and it cost £700, using Bedec Barn Paint.

 

[meccarroll]

Our walls are solid timber logs clad outside with pine boards. When repairing a small area (the outside of one room) we added new cladding over the top of the existing. We did this to avoid the work of removing the old cladding and also thought it might add something to the insulation. That hasn't caused any problems so if I were faced with the same choice again I would over-clad rather than ripping off the existing cladding. I can't comment on the choice of oak as the cladding material.

Interstitial condensation occurs within wall fabric, it's where warm moist air meets the cooler outside part of the wall forming internal condensation within the wall and so may not be detected from surface finishes until damage has already occurred. If you already have an internal vapour barrier then the vapour barrier should greatly reduce any risk of interstitial condensation happening because it's job is to stops tiny particles of vapour passing through to the wall and causing interstitial condensation. Probably better to consider pro's and con's of each option before proceeding.

 

[Just4Fun]

Interstitial condensation occurs within wall fabric, it's where warm moist air meets the cooler outside part of the wall forming internal condensation within the wall and so may not be detected from surface finishes until damage has already occurred.

I guess it is true that our wall could be rotting from the inside outwards and I just don't know it yet. I find that hard to believe though; I don't see why a double layer of cladding on the outside can be worse than a single layer. If anything the temperature gradient across any part of the wall's cross-section will be lower so I can't see why condensation would be more likely. However this is just wild-*** guessery based on zero expertise.

If you already have an internal vapour barrier then the vapour barrier should greatly reduce any risk of interstitial condensation happening ...

I can follow your logic there, but I gain little comfort from it. There is no vapour barrier in our walls. From the inside out there is some soft fibreboard, battens, solid logs, battens and outside cladding. Plus the extra cladding we added on a small area. Locals here have advised against adding any insulation that includes any sort of vapour barrier. They say this type of construction needs to breathe and if you interfere with that you cause problems.

 

[meccarroll]

I guess it is true that our wall could be rotting from the inside outwards and I just don't know it yet. I find that hard to believe though; I don't see why a double layer of cladding on the outside can be worse than a single layer. If anything the temperature gradient across any part of the wall's cross-section will be lower so I can't see why condensation would be more likely. However this is just wild-*** guessery based on zero expertise.

We used to have chimneys with a flue and ventilation, cook over a vented oven, leaky windows too so lots of ways to disperse any moisture build up long before it reached the internal fabric of the walls. Now we have microwave ovens, dishwashers, washing machines, tumble driers, showers etc adding to a massive build up of water vapour internally and of course central heating creating enough pressure to force it into the wall fabric. Older timber framed buildings that do not have a vapour barrier are not really designed for todays modern living standards.

If you already have an internal vapour barrier then the vapour barrier should greatly reduce any risk of interstitial condensation happening ...

I can follow your logic there, but I gain little comfort from it. There is no vapour barrier in our walls. From the inside out there is some soft fibreboard, battens, solid logs, battens and outside cladding. Plus the extra cladding we added on a small area. Locals here have advised against adding any insulation that includes any sort of vapour barrier. They say this type of construction needs to breathe and if you interfere with that you cause problems.

This is of no consequence as you have not added insulation just cladding.

 

[AJB Temple]

Thanks all. To clarify.
The barn was converted in the 1980's (not by me). It is already insulated, has a breather membrane and clad.
There is not much rot - it is mainly window surrounds - I could do repairs in a couple of days.
It is not listed. Nor is it visible from any road or footpath and we are not in sight of any listed building.
It is already painted black.
My painting cost of £3k was high quality paint plus scaffolding. I assumed I would do the painting.
The oak I have is already planked and has been seasoning indoors for about 30 years. To me the oak is free. Cedar would not be free.
I have clad barns in oak before (from this stock) and had no issues with cupping and durability.
I am aware of the Japanese burnt style and like it but it works best with vertical timbers.
Not sure that fire risk is increased with a second skin. It's already an oak barn full of oak floors and joinery and covered in wood.
We have no damp issues now.
I reckon I can clad the whole building in oak faster than I can paint it. Pretty much for free (apart from milling costs), except for some marine grade stainless nails for my nail gun.

As an example I built two oak framed large double garages with cat slides and log stores in the last year or two and clad the pair of them in oak on my own in a day. Obviously a whole house, with windows etc is a bigger deal and much higher, but I already have an industrial scaffold tower and more tools than anyone actually needs, so I think I can easily do this with a helper.

I also like the look of natural oak as it ages and goes grey. Of critical importance, so does my wife.

I am not sure what I gain from stripping the existing cladding off. To me, I am adding an extra layer of insulation with my crazy plan. The building is already pretty well insulated, but I could add another membrane and some more insulation.

Really, I don't see much difference between my proposal, and the outcome had the building been clad with two inch thick planks (log cabin style) in the first place.

We plan to stay here until I die. So it needs to last forever
Realistically I am seeking ultra low maintenance and a lifespan of 20 years, after which we will give it to offspring and live somewhere warmer.

It is however a really genuine question. I am not sure if I am missing something as I am no building expert. The actual woodwork does not worry me in the slightest. And I am expecting to be out of my business shortly so I will need something to do.

AJ