Poplar in Timber Frame Buildings

Hi,

In discussions today with the Oxfordshire Woodland project manager here in SE England we explored the possibility of funding a trans Atlantic trip for an American timber framer who has experience in the use of poplar in timber framed buildings.

Considerable amounts of this material is growing here and has now reached useable size however there is no longer any significant market for this wood. Previously most of this material went for making matches and is now used mainly for kindling wood.

We are exploring the possibility of establishing new uses for this wood and as far as we are aware there is little practical experience here in the UK of its use in structural situations.

Practical input into matters concerning both design and construction using poplar would be required.

Anyone with the requisite experience can register their interest by sending me a PM.

Regards

Ken Hume

Ken,

What is the genus and species of poplar you are referring to?

In the states we have quite a few species of poplar (populus spp.) and then we have yellow-poplar (liriodendron tulipifera) which is commonly called "poplar" and occurs over most of the Eastern US and which is not a true poplar like aspen or cottonwood. I'm afraid there may be some confusion without specific epithets.

Ken:

Poplar/Aspen like we have here in Maine has a lot of value for the "Engineered Wood Products" industry. (The nemises of timber framing and its future, some would say).

Poplar veneer is in high demand for cabinet grade hardwood plywood substrate. Smaller logs/ tree tops are also harvested for chipping and made into OSB... the sheathing in 90% of homes today.

This company is making big money w/ poplar in northern Maine.
http://www.huberwood.com/main.aspx?pagename=advantechsheathing

Hi Gabel,

The poplar is a clone between P. Nigra and either P. Deltoides or P. Trichocarpa.

P.Nigra is European black poplar and this was sometimes used for cruck blades and in mill work. The others are poplar imports with P. Trichocarpa being Western Balsam poplar and P. Deltoides being American Black poplar (cottonwood).

It is now quite difficult to tell the exact composition or make up of these trees but any knowledge of the use of timber from any of these poplars might give some indication as to possible end uses.

Regards

Ken Hume

i have hewn timbers out of balsom poplar (we call it balm of gilead poplar in northern ontario, canada) and it is not the most pleasant wood to cut. even where there are no big knots it tended to tear out. this may have been twist in the trees, but they looked like they would cut nicely.

also, when fresh cut it smells like beavers. probably no coincidence since that's what they like to eat.

this is a very good species for sauna benches though. easy to get clear material, the wood isn't dense and so doesn't get too hot for your bottom, and since it's very pale it can be bleached to clean without turning ugly.

Hi Toivo,

That's an interesting take on poplar. Beavers have just been reintroduced into England from mainland Europe onto controlled sites but there is now evidence of some having escaped or been released into the wild. I saw beaver cut tree stumps by the river Thames in Oxfordshire recently and was informed that a North American beaver had been captured.

"Tearing out" of surfaces is something that happens especially when blunt tools are being used and certainly waiting till the wood dries somewhat can help in this respect on timber that is prone to this behaviour. Traditionally poplar has been used to form truck and railcar beds where it does not crack but crushes and yields instead and this appears to match your own experiences when converting this wood but I have found that even freshly felled Douglas Fir is prone to tear out of the grain.

Since making my original post I have now found one barn that is made from poplar and a mill that contains poplar beams. The exact species employed is not known but I am now very much aware of the hybrid nature of many poplars growing in the UK with North American poplars (populus Canadensis) now forming a key part in the make up of planted poplars in the UK. These trees grow exceedingly well in the UK forming nice straight stems and quickly putting on volume.

Large black poplar can be found growing in South Oxfordshire in relative abundance and this poplar species is known historically to have been used to form cruck blades so even though it is classed as a perishable wood somehow it manages to fullfill this demanding role.

Regards

Ken Hume

that's all very interesting Ken. beavers on the Thames! wow

in terms of poplar's property of 'bouncing back' (i'm thinking balsom poplar here) i am aware of the species being used as the bed for skids. apparently it deals with heavy equipment cleats better than other harder woods.

what was your experience with the poplar you saw in historical frames in terms of stability? any twisting?

I'm busy right now with some poplar as well as having worked with it to a limited degree over the past 5 years or so. Actually, in times past, it was regularly and widely used in places like France, Belgium and Holland at least.
Anecdotally speaking, in France this timber was preferred over oak for use in horse stalls because it did not react to the ammonia given off by horse urine. Many a hay loft floor of the barns around here were poplar because of its wear resistance due to its long fibers which also makes it not such a pleasure to work with hand tools but it is true that working it dry helps.
My hay loft, which is now where I dry wood, has new poplar floor planks, 35-mm thick and some up to 40 cm wide at one end. It's stable given that it is dried with a bit of care. I use it whenever I can get a hold of nice straight looking trunks, and it's free.

Don W.

Hi Don,

That is all very interesting information and I am pleased that the forum has now managed to include contributions from The Netherlands. We look forward to hearing more about your building heritage and experience.

Regards

Ken Hume

This is quite old, but I will still add my limited knowledge for whatever it is worth.

In Midwest USA, Eastern Cottonwood was traditionally the preferred material for barn and hay mow floor boards. This is because of the property mentioned earlier, that it will not be crushed and torn up by heavy machinery but instead mush and then spring back. In this application it is said that cottonwood boards last a very long time. The wood seems to handle stress well. I had once heard, though have been unable to find any evidence to support this claim, that cottonwood was once also used for shakes. This seems doubtful to me, but you never know how much different hand worked word acts!

Cottonwood tends to grow very fast, very tall, and very straight, at least around here it does. It is also considered by most to be a pest. It can quickly spread into drainage channels and clog them up, which is a nuisance for farmers. No one wants to use the lumber from the trees for anything other than pallets these days, so it remains mostly uncut. As a result we have a lot of very old, large cottonwoods around. The old timers used to say that the bigger the cottonwood, the better it was on the saw, They would saw as big of logs as they could handle.