Weatherboards to seal or not to seal?

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wlgtraderx

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#248666 4-Apr-2019 21:20

Hi all Ive recently brought a 100 year old character type home. I've now had had three painters come and look at some rough paintwork. They are had variances on the same story was that I need to go back to bare wood and re-paint the whole old section of the house as there is too many layers of paint and the prep underneath and some products were not good, causing crocodile texture/crackling/bubbling etc in quite a few places, and would only get worse...

Anyway one of the guys was saying don't seal any horizontal gaps in your weatherboards where they meet, as you need to let some breathability remain to air any moisture behind the weatherboards.. The other to said seal it all up, except new weatherboards which need to settle/dry for a period.

What is your view? I would have thought the whole idea of the cladding was to be totally sealed (as much as is possible).

These are vertical type board with the scallop indent at the top we’re meets the one above.

Thanks

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#2210962 4-Apr-2019 21:23

That gap will move as they expand and contract. Ones I have seen where it is sealed up good with acrylic sealer tended to have a lot of splits in it on the thin part. No idea if the sealer glued it together enough to cause it to split longwise on the thin part of it it was just coincidence.

Check if its got any lead paint at any layer on old places.

Also check if its cheaper to reclad it in something more modern then spend a fortune on remedial work if most of the boards are shot.

Richard rich.ms

timmmay

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#2210966 4-Apr-2019 21:28

I just had my old house stripped and painted. It was bubbling and cracking because the cedar weatherboard was never prepared properly. I'd get bubbles that had water in them.

I had them seal all the weatherboards gaps. There should be building paper behind the weatherboards, but this old who knows what's there. It's had holes drilled on the outside to put insulating foam in, so any building paper would have holes in it anyway... probably should've thought of that before I had it done.

If you reclad with a different material you may have to bring the house up to current building standard. I vaguely recall that can require a gap between framing and weatherboards, which means all your windows would have to be redone.

Repaint isn't bad. If you're in Wellington I can tell you who I used, I'm happy with them. Just make sure they're very careful with lead paint controls - my painter was pretty rubbish at that until I had a pretty good go at them.

tdgeek

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#2210974 4-Apr-2019 21:45

Our last place we reclad. We were told if you cant quite get your fingernails in the gap, its fine, as the coats of topcoat will seal it. If larger, seal it. I used some Bostik type of flexible exterior goop, its great. We had the ChCh EQ's after that, not one gap, crack, its flexible.

Leaving a gap to breathe??? No way. Its warm inside, maybe the walls are not insulated, the cold wet air will be sucked inside. And the possibly old untreated or whatever they did back in the day framing and lathe and plaster.

wlgtraderx

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#2210993 4-Apr-2019 22:01

Thanks all, sounds like sealing is a go. Yeah no appetite to reclad, apparently the boards seem mostly ok. Am preparing for some expensive quotes .. but trying to remain philosophical, should get 10 to 15 good years from here on the repaint and all that.

timmmay

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#2210997 4-Apr-2019 22:16

Once stripped make sure they use an oil based primer / sealer / undercoat. Dulux 1step oil based is what I used. Water based paint can go over it.

tdgeek

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#2211001 4-Apr-2019 22:21

wlgtraderx: Thanks all, sounds like sealing is a go. Yeah no appetite to reclad, apparently the boards seem mostly ok. Am preparing for some expensive quotes .. but trying to remain philosophical, should get 10 to 15 good years from here on the repaint and all that.

As Timmay probably implied, DONT SKIMP on anything quality wise, or prep wise. An extra few dollars or extra pedantic time will pay for itself.

Bung

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#2211005 4-Apr-2019 22:34

wlgtraderx:These are vertical type board with the scallop indent at the top we’re meets the one above.

These are "rusticated" weatherboards. They've lasted 100 years because any water getting in had a way of getting out and air movement dries any wet timber. If you were starting today wanting an airtight wall the weatherboards would be on cavity battens over an underlay.

"Rusticated horizontal timber weatherboards
Rusticated board cladding systems are very air leaky. The thin section of board that overlaps the rustication tends to move and distort, and this allows air to enter at the lap. There is also the potential for rainwater to be driven in at the lap, but this distortion lets water drain out as well.

While rusticated boards have good potential for air entry, they do not have the void of bevel-back boards, as they fit hard to the wall frame (with a high contact area with the wall underlay) and do not have as good a drainage and drying capacity."

https://www.weathertight.org.nz/new-buildings/detail-solutions/wall-cladding-selection/weatherboards/

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froob

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#2211008 4-Apr-2019 22:40

I think the wisdom these days is that the gap between weatherboards should not be sealed. See for example this article from Build magazine:

https://www.buildmagazine.org.nz/assets/PDF/Build-150-33-Build-Right-Installing-Bevel-Back-Weatherboards.pdf

“This resurgence has highlighted a shortage of tradespeople experienced in bevel-back timber weatherboard installation. Issues with installation recently seen include:
...
* sealing of the board laps – this is not recommended as it restricts drainage and drying.”

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bfginger

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#2252764 6-Jun-2019 09:19

Old houses can have lead paint and you don't want that sanded down without thought.

esawers

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#2252794 6-Jun-2019 09:49

Had our whole house prepped and painted a few (8) years ago and it looked like the paint was cracking between the gaps.

The painter was reluctant but he filled in all the gaps with flexible sealer. We haven't had any problems.

tdgeek

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#2252805 6-Jun-2019 10:08

esawers:

Had our whole house prepped and painted a few (8) years ago and it looked like the paint was cracking between the gaps.

The painter was reluctant but he filled in all the gaps with flexible sealer. We haven't had any problems.

Flexible sealer is great. Its rubbery. We reclad before the EQ's in Chch, no issues.

Fred99

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#2252827 6-Jun-2019 10:54

bfginger: Old houses can have lead paint and you don't want that sanded down without thought.

IMO that's "probably will have".

If it does, then I'd measure area of weatherboard, divide cost of (responsibly carried out wrt containment of lead) paint removal/repainting quote by how many square metres, and consider that cost of new treated pine boards, installed and painted is probably about $200/M2.

Then balance that out considering that recladding would allow fitting of insulation, building paper, upgrading flashings etc, so the end result would be a warmer, more comfortable house.

At least that's a starting point, it may be that a reclad would involve a lot of mucking around getting window/door facings to work and up to building code and would make the project tricky and uneconomical. Council consent process and cost for "like for like" recladding may vary from place to place. (You could reclad like for like in Chch and insulate at the same time without building consent a few years ago - post EQ, but I'm not sure if that exemption still applies).

I expect removal of the paint and prep for repainting is going to be expensive, and in the end you've still got the performance of a 100 year old house. It may be an opportunity to make a significant improvement.

timmmay

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#2253007 6-Jun-2019 13:44

Recladding and bringing up to current code could be incredibly expensive. For example (from what I've heard only) you may have to create a cavity between weatherboards and house, which means moving out replacing all windows. That's what a builder suggested when I was considering that.

My house has about 200 square metres of weatherboards. Repaint was $16K cheapest quote, about half that was striping lead paint with a heat gun. They were terrible with containment, wet removal is strongly recommended.

Fred99

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#2253038 6-Jun-2019 14:20

timmmay: Recladding and bringing up to current code could be incredibly expensive. For example (from what I've heard only) you may have to create a cavity between weatherboards and house, which means moving out replacing all windows. That's what a builder suggested when I was considering that.

My house has about 200 square metres of weatherboards. Repaint was $16K cheapest quote, about half that was striping lead paint with a heat gun. They were terrible with containment, wet removal is strongly recommended.

Sure - it could be very expensive - but then again it might not be. I think for the OP, it might be a good idea to find out. Windows on weatherboard houses usually have internal reveals - so they may even be able to be shifted out 20mm and fitted back relative to the cladding in the same place after fitting cavity battens.

When I reclad our place, which was partly directly fixed WB (no battens) windows and french doors in that area were left exactly where they were, sills were extended to allow for the extra 20mm (using matching timber, SS screws and epoxy adhesive), I fitted new facings and scribers, head flashings etc (under supervision of a licensed builder, and fully consented), it really wasn't a huge job. Yet assorted experts told me the best option was to replace the windows - which would have cost a fortune and looked horrible - unless I spent a mega-fortune. It would have been quick and simple though. You don't need just any licensed builder, but one who's experienced in renovating old homes.

If the paint job you'd had done for $16k was done properly (dealing with the lead), how much extra would it have cost? $16k to strip and repaint a house with 200M2 of W/B cladding sounds very cheap to me.

timmmay

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#2253166 6-Jun-2019 15:39

The highest quote was $22,000. I don't know how much longer it would take or how much more it would cost if they had use paint stripper, which as a wet process produces far less dust.

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