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Tantalised Roofing Battens

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JAW911

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I am re-roofing a logstore with Western Red Cedar shingles. I am covering the original roof supports with sheet ply covered with tyvek. Then I intend to fit ten 2.4m battens 19 x 38mm tanalised. I can only currently get 25mm thick which are too thick for my liking. My question is if I run these 25mm battens through my thicknesser will I reduce the effectiveness of the tantalising? Am I better being a bit more patient and waiting for the 19mm to be available again. Stocks are so short during this pandemic as we all know. Can anyone help please? Thanks
 

Woody2Shoes

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Why too thick? A slightly bigger batten is less likely to split when nailed and likely to last a little longer in service. You will impair the effect of the tanalising by slicing 5mm or so off the thickness - to what extent and with what downside is open to question. I'd just use the battens as they are. Cheers W2S
 

JAW911

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Thanks to you both. I just felt that an inch was too high for the shingles to sit. I guess I will buy them and see. Sounds as though any planing will need treatment - thanks for the recommendation.
 

Inspector

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From what I understand your cedar shingles will not last. Without airflow behind the shingles from eves to ridge or across with gable vents the shingles won't dry out and eventually rot. You should have strapping run from eve to ridge and then battens across the roof. Goes without saying you need ridge and eve venting. Why cover with plywood and tyvek instead of leaving the shingles exposed on the inside? Here the battens would be 1x4 (dressed they are 3/4"x3 1/2", your 20mm x 90mm) nailed directly on the rafters and the shingles to them. Done right the shingles will last decades. Wrong and you replace them every 10 to 15 years.

Pete
 

Spectric

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Thats how the roofers did my shed, I had boarded it with 18mm sterling board and painted it with bitchumen, they ran battens vertical before attaching the horizontal battens to which the tiles were nailed and fitted air vents on the ridge line. All to ensure airflow to keep the structure dry.
 

Woody2Shoes

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Yes - upwards from rafters you want: ply, membrane, counterbattens (along the rafters) then battens and then shingles.
 

TheTiddles

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The ply and membrane seems a bit nugatory for something that’s open under the roof presumably
Aidan
 

mikej460

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I also think it is overkill for a log store, but it is your log store so if you want to board it (sarking) then this is what I did on my outbuildings and will do next year on my new workshop. Sarking boards nailed to rafters, Vertical battens onto to sarking through to rafters, breathable membrane stapled onto vertical battens, horizontal battens across membrane at correct gauge (spacing) and cedar shingles and ridges nailed with stainless steel nails. Although I've built a slate roof this was my first cedar over sarking, it was hard work and I spent a lot of time reading web pages and watching YouTube before and during the build.

Shingles Going On.jpg


Roof Finished.jpg
 
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JAW911

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Thanks for advice everyone and fir the pictures and explanation mikej460.
As I now understand it...plywood sarking then horizontal battens onto sarking, then vertical battens, then tyvek onto vertical, then horizontal battens?
 

mikej460

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Apols I made a mistake on my post (now corrected) its should be plywood sarking then vertical battens onto sarking at rafter spacing then tyvek stapled on to verticals, then horizontal battens nailed then shingles.
 

JAW911

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Yes it did seem to be a lot of battening. That makes sense. Thank you. What size battening is that please?
 

Hornbeam

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Membrane type and position will have a massive impact on the durability of the construction. The key in all cases is to confirm the position with the manufacturer. Looking at the image of Mikes roof with the membrane over the counter battens I cannot see how this will provide effective ventilation for the back of the shingles as the battens prevent air movement up that part of the cavity This would not really be an issue with nor rotting/corroding tiles. A better position would be underneath the counter battens
When installing membranes between counterbattens and battens the membrane must be left slack to allow any water to drain and not have the battens act like a dam.
For a simple woodstore I would leave out the sarking completely as this will allow free air movement to both under and top side of the shingled
Also note that sarking in older properties generally had gaps between board due to shrinkage which allowed air movement /ventilation. Modern sarking with OSB does not allow this
 

mikej460

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I would add that I used a quality breathable membrane which is an acceptable solution for installing a cedar shingle roof and I followed the suppliers instructions. However, I agree with others that in your case sarking really is overkill, I wanted to add a warm layer to stop condensation when my animals are housed in the loose boxes and chose to used tanalised T&G as it looks nice in my adjoining toolshed. I would add that I to have a log store, the roof is made from tanalised feather edge board but on a very low angle so I nailed it over a breathable membrane and it workworks very well. In our last house I built one with a steeper slate roof with no membrane and that was also water tight.
Tool shed ceiling.jpg
 
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