I have this kind of boarding on my roof, it's quite standard, though I'll be darned if I can remember the EN word for it (Bourth, where are you?)

But it's that 'disjointe' which puzzles me... often / usually, this kind of boarding is immediately beneath the tiles (slates, etc.), i.e. ON TOP OF the rafters. I don't imagine that this means that the boards are LOOSE (!), but I wonder if it could mean that they are fitted to the UNDERSIDE of the rafters (as is sometimes done) --- one might interpret that as being 'disjoint' from the actual roof covering itself.

This latter type is referred to as 'soffit', and in fact it seems the same term is also applied to the 'on top of rafters' type too.

Sorry I can't be more positive help, but hopefully that might give some food for thought at least.

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Note added at 53 mins (2006-06-18 17:15:10 GMT)
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Re: Jeff's question

The only term I've encountered for 'voligeage' (where it does not have anything specifically to do with the eaves) is 'boarding' --- we talk about a roof being 'boarded and felted', for example

So you see how one word 'voligeage' changes its translation in EN as its position on the roof changes, becoming 'soffit' once it arrives at the eaves!


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Note added at 56 mins (2006-06-18 17:17:54 GMT)
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Of course the 'disjointe' MIGHT just mean they are plain boards --- because here in France, tongued-and-grooved boards are VERY OFTEN used for this purpose. Thinking about the way it is being used in the sentence, that could make a lot of sense:

"Underside of eaves: treated, plain-boarded soffit"

or words to that effect...

I believe this is the term in English, used a lot in Scotland. Traditionally timber boarding was used but now timber based panels (plywood or OSB for example) are used instead. Volige would be the traditional sarking, the timber boarding type. I agree with Tony that disjointe probably means plain or square-edged boarding as opposed to tongue and grooved.

From my notes:

Voligeage Roof boarding, battens (voligeage-boarding with scantling, chanlattage-boarding with cant boards)

Voligeage continu Close boarding

("voligeage" being made up of a series of "voliges" or planks).

I would have suggested "hit-and-miss boarding" but the Dict. of Arch. & Const. (Cyril M. Harris) appears to suggest "spaced boarding".

In U.S. usage, a roof is first "sheathed" before it is covered by its final roofing material.

Though originally wide boards were used (usually not with spaces in between, though spaces could form later, as the (sometimes "sawmill green" wood shrunk), nowadays the sheathing consists of sheets of 4 foot x 8 foot plywood or "particle board".

These are then typically covered with a layer of tar paper, and finally with shingles (originally made of wood, now usually of asphalt).

Here's the OED on "sheathing":

"A covering or envelope in which something is encased for protection or ornament; material prepared for use as an envelope or casing. Chiefly in technical applications: e.g. a covering of boards, plates of metal, or other material, fitted to the surface of a wall, roof, or other part of a building, a piece of machinery, or the like."