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By sploo
#1197383
The wife wants me to make a lean-to style greenhouse, and for it to be painted.

Having read a recent thread on this site about linseed oil paint I thought I'd try that.

The supplier I'm talking to indicates that untreated timber is preferable, but I'm wondering if it's worth using cedar instead of pine? I.e. once painted with linseed oil paint, is there likely to be any longevity benefits of cedar vs pine?
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By ED65
#1197400
Assuming no direct soil contact you could be fine with a species that doesn't naturally have rot resistance. Certainly many softwood window frames etc. that were originally painted with oil paints have stood up surprisingly well,

One thing that complicates the picture of how well linseed-oil paints work to preserve woods is it's difficult to know for sure what species were used in the woodwork that has lasted and whether that's the major factor. Then there's what maintenance was carried out over the decades that contributed to them enduring, plus other unknowns that may have aided such as a shielded location, good airflow and other things not immediately evident to casual observation.

Also something I harp on about a bit, we mustn't forget that the quality of the wood back then could be very much better than what's commonly available now and better wood (slower-grown) is most definitely of great benefit. And in somewhat the same token certain pigments used back then (that are banned now or only available through specialist suppliers) acted as preservatives even though that's not the reason they were used way back where.

So it would be best to use a species that does have a better track record outside. Belt and braces and all that.
By Jacob
#1197404
Redwood will be OK. I don't think the quality has changed. No point in expensive cedar if you are going to paint it.
More important than the species is the detailing - especially at the bottom where verticals meet wall plates and there can be water traps. Bottom edge of sheets of glass ditto.
By garethharvey
#1197419
I am literally about to finish my glasshouse build, I used pine about 7/8 years ago, I now have to remake the entire structure.

A forum member put me in contact with a Western Red Cedar supplier, the cost is not that more expensive than pine.

The linseed oil paint works very well but you need to paint the Cedar as soon as it is exposed to the sun.

Supplier was: https://www.southgatetimber.co.uk