Thread: Why are weatherboards tapered?

I think it's to cater for the overlap. Using a rectangular section, would mean that the overlapping board will be further off the stud.

I thought it was because you could get better utilisation of a log using quarter sawn tapered boards. Effectively you can use almost the entire log minus the saw kirf if you don't dress them.

I think both of those points are valid. If you look at the end of a weatherboard wall, you'll see a covering strip, which would need to be twice as thick if the boards weren't tapered. Also, square boards would have a surface which is further from vertical, which would mean the surface would deteriorate more quickly, from increased sun damage and increased water retention.

What about warping? Wouldn't a thinner section mean less warping? and less force pulling the nails out when it does warp?

With circular saws you start with a 175x38. Bolt a taper to the bench saw fence, set it to the right width and slice the timber, holding it against the fence.

If you used non tapered boards then you'd need a 175x56 to cover the same amount of wall. Ie. with tapered weatherbeards you use less timber for the same amount of wall

But couldn't you just use thinner boards, rather than tapered boards? A 38mm board cut into two 19mm boards covers the same wall space as a 38mm board cut into two tapered boards doesn't it?

Bah, that only makes sense. I didn't invent tapered weatherbeards

But you woulda done if someone hadn't beaten you to it?

If they were "square" Rectangular in shape then they would be calle "Ship Lap" siding.

Actually the taper gives better protection from the elements. With the overlap and a thicker bottom , the rain is shed further away from the underlying board, thus protecting it from Capillary action where the water runs back under and into the joint.

also lets you know which side is up, And the wedge shape allows the gap created by the overlap to be smaller and still maintain the thicker board to fight the elements. Think about it, If the board was a full 3/4" thick , then the space behind the overlap would be a full 3/4" with a taper, it reduces the gap, yet still provide the thicker leading edge where the perils of the weather fight back.

Same holds true with Shingles, Tapered from a thick leading edge that is exposed to thin under the overlap.

Remember that the clapboards were a mimic of the shingles. Or was it the other way....?

OK some reasonable reasons there. Isn't shiplap where you cut a bit out of the outside top of the board and the inside bottom? Like a T&G cut down the middle.
My tapered weatherboards are 5 to 20mm and the flat ones I cut 15mm so the flat ones stick out a bit more from the wall about 30 rather than 27mm, they are also more inline with the wall. The saving in wood is substantial. Flat boards can be turned in any direction so you have less rejects. Thin strips can be cut from the same reject board rather than just the bottom of one board. less hassel to mill and dress (if you want to) I'm thinking I will not make tapered boards next time aswell.
Thanks for the input everyone.

BUT.... Remember, the "Always done it that way" rule applies...

You are right about the Shiplap....

When one of our neighbors was building a new house they used complete logs cut into segments (like an orange), and supplied as the original logs. Like this:

http://www.rc1.com.au/spec/ehc_NaturalEdge_Spec.pdf

The blurb claims that radially sawn boards are more stable, and I suppose it maximizes the yield. I wonder if it was the traditional way of doing it? It would be easy to do, just keep turning the log and making another cut.

I suppose that like most of these things there is no single reason, all of the things people have mentioned were factors.

I believe this radial sawing is quite recent a Mr Knorr started it. Son of the wood carver that lived in Myrleford. It may well have started this way though as this is how they split logs then trimed with a broad axe or adz. Would be a hard job with a crosscut saw.

Originally Posted by glenn k

I believe this radial sawing is quite recent a Mr Knorr started it. Son of the wood carver that lived in Myrleford. It may well have started this way though as this is how they split logs then trimed with a broad axe or adz. Would be a hard job with a crosscut saw.

Me thinks you give Mr Knorr too much credit.... Check this out: Clapboard (architecture) - Wikipedia, the free encyclopedia

Clapboard, also known as bevel siding or lap siding or weather-board (with regional variants as to the exact definitions of these terms), is a board used typically for exterior horizontal siding that has one edge thicker than the other and where the board above laps over the one below. It is often found in New England architecture.
Clapboard siding got its name from the Dutch Klappen, meaning to split. It was originally split by hand from logs in a radial manner. Later, the boards were radially sawn in a mill.

In Australia and New Zealand, this kind of cladding is known as weatherboard, and was extensively used in forested regions from the Colonial period to the mid-20th Century.d siding got its name from the Dutch Klappen, meaning to split. It was originally split by hand from logs in a radial manner. Later, the boards were radially sawn in a mill.

Maybe so but he is trying to promote radial sawing here;
Radial Timber Milling
It appears others are trying to; Radial Corporation
Certainly in the old days everything was split and trimed it would have made the most stable timber, but sawing like this with a cross cut is not on. And traditional saw mills never radial saw. When I did my grading course I asked the mill instructer about radial sawing he laughed and said it's great if you want triangles, but if you cut standard boards from these there is a huge amout of waste, but top quality quarter sawn timber. Another fellow who was an instructor there told me they had a forestry student that was working on a paper discussing different milling techniques come to the mill they gave him some info on radial sawing he didn't bother taking it with him.