Is Western Hemlock Suitable for Doors and Window Sash?

A discussion of the properties and best use of Hemlock. September 7, 2013

Has anyone has used hemlock lumber successfully in the fabrication of sash and door?

Forum Responses
(Architectural Woodworking Forum)
From contributor S:
Some of the characteristics that make hemlock desirable for covering barns also make it a decent choice for exterior applications such as doors and windows. I've used it a bit for both and find it holds up well and it pretty stable. It is not pleasure to work with, being coarse and prone to splinter, but is stronger and more rot and bug-resistant than pine, as well as being cheap.

From the original questioner:
I should have specified western hemlock but overall I am coming to the conclusion that yellow cedar and Port Orford cedar seem to be much more durable than hemlock (especially yellow cedar). In fact yellow cedar might be an excellent material for stain and paint grade sash and doors. I have been using exclusively V/G doug fir for years but good stock is getting really hard to find.

From contributor S:
I've left sample pieces of several species in ground contact in the humid Southeast for months and years at a time and I can tell you that white pine will rot dramatically faster than hemlock. Ironically many 150 plus year old buildings are sitting very well on heart pine timbers (hopefully not in direct ground contact, but nevertheless).

I respect the work of those that have done the research, but think there might be room for some new information. There is a reason hemlock has been used extensively for siding in its native range and you can be darn sure it's not because it rots quickly (pretty much the first criterion for siding). If you have access to yellow or Port Orford cedar you'll find them much more suitable for doors and sash. I would go with those any day over hemlock, but I would not discount it out of hand as some do.

From Gene Wengert, forum technical advisor:
Western, but not eastern is used for millworkers - avoid sinker logs.

From Contributor D:
Here in the PNW we have the western hemlock and also what is called Hemfir - a hybrid that is faster growing and apparently harder than hemlock - it may be used for framing material. Typically hemlock is used here for paint grade trims and molding's and other non-structural applications. I was asked to make a good sized mirror frame some years back from hemlock and won’t again in an application where the boards need to be cope and stick.

From Contributor O:
I will add that I think the entire conversation about exterior stability/durability needs to be reframed using terms like first growth, or tight annual rings. This could easily render the earlier FPL work I referenced obsolete. The fact is that old growth - slow grown trees in fully matured forests - almost always has greater stability and exterior longevity than subsequent cuts. A single case in point is 150 year old historic structures in Indiana built with poplar logs from the original old growth forest, while new poplar put in exterior use will grow mushrooms in two-three years.

Spanish cedar, some western red cedar, Honduran mahogany and other woods considered stable and durable are in fact old growth cuts, while the current crop of redwood, cypress, some western red cedar and others are second or third generation cuttings. What they have in common is a low annual ring density. What the durable species have is high ring density.

If my wildly unscientific conjecture is true, it could be that some first growth hemlock - reclaimed, logged or risen from the waters - could be a good stable wood for exterior work. It may be a better choice than some recent growth in redwood, cedar, VG fir or cypress.

From contributor U:
Hem-Fir is not a hybrid of two species. Hem-Fir is a category of lumber that includes a large number of western wood species lumber that behaves enough alike to be treated as one species for grading in the market.

In the Western Woods region, the 12 contiguous Western states plus Alaska, there are approximately 20 commercially important species well suited to softwood lumber production. While each has unique characteristics, physical and mechanical working properties, making it appropriate for specific applications, these Western softwood species are grouped into six primary combinations. These combinations simplify production, inventories and distribution, and facilitate engineering and product specification for design.

Hem-Fir is a species combination of western hemlock (Tsuga heterophylla) and five of the True Firs: California Red Fir (Abies magnifica), Grand Fir (Abies grandis), Noble Fir (Abies procera), Pacific Silver Fir (Abies amabilis), and White Fir (Abies concolor). While western hemlock and the true firs are sometimes marketed separately in products graded for appearance, these species share similar design values making products graded for structural applications interchangeable. The Hem-Fir species combination is one of the most important in the Western region, second only to the douglas fir-larch species group in terms of abundance, production volumes, strength, and versatility in end use.