Workshop massing sketches

← Back to workshop series indexPublished: 2016 July 31Last updated: 2016 August 4

With the workshop site chosen, I can now sketch out the workshop’s rough shape.

I prefer simple shapes that support the fundamental functions of my building:

• keep out rain + wind
• let in light + air
• buildable by an amateur individual / small crew

A rectangular shape would be the simplest for me to build, and I stylistically prefer shed (monoslope) roofs over gables.

For optimal use of space, the carport should be closest to the slope: The carport is lighter and would better tolerate shifting soil than the workshop slab. (My Mazda3 hatchback weighs 33 psf; even with 25 psf for 3" of carport gravel it’s lighter than the 75 psf for a 6" slab, not to mention the weight of the building itself).

That gives an overhead view of something like this (North is up; downslope to the West, upslope to the East):

The other key factor relevant to massing is the workshop’s thermal and airtightness performance requirements: Can it be a covered outdoor space or does it need a full-featured building envelope?

The following massings assume the latter.

I came up with three options for the roof (looking from the workshop’s South face):

All have an open carport on the West side (near the downslope) and a glass door on the South face to let in daylight. (TBD: sliding vs. overhead doors.)

The first, massing A, is the simplest: a shed roof covering both the workshop and carport with the high side on the East.

The minimum pitch for a metal roof to effectively shed rain is about 3 in 12 (arctan(3/12) ≈ 14°). So if the workshop + carport is 36’ wide and the low side is 8’ high, the high side will be about 17’ high.

Pros:

• Likely simplest to design+build
• Water drains to the West, which slopes downhill away from the structure
• Glass door is in a non-load bearing wall, which may reduce engineering and material costs (no giant headers)
• Clearstory windows in high wall would face East/Southeast, which makes for good light
• Roof not visible from anywhere else on property, and can be economized
• High East ceiling required by roof slope doesn’t interfere with doorway and could be used as material storage

Cons:

• Might look stupid/boring — in particular the long single roofline
• Tall Eastern wall would visible during drive onto property and from residence, so it’ll need to look nice

The second, massing B, has the workshop roof sloping North-South, with the carport roof sloping East-West.

Pros:

• South-facing clearstory windows on workshop provide most light
• Neither workshop nor carport roof visible

Cons:

• Glass door in load-bearing wall
• High ceiling on same side as doorway, so would be more difficult to use as extra storage space
• Carport may look stupid, have complicated flashing and siding details where it meets the workshop
• Drainage at rear of workshop needs to be diverted (gutters, or just reshaping ground?) so it doesn’t flow into workshop foundation
• North-South roof span may be longer than East-West, requiring more expensive trusses

The third, massing C, splits the roofs.

Pros:

• Garage door on non-load bearing wall
• Clearstory windows in high wall wouldn’t be visible from elsewhere on the property and could be made out of ugly/cheap materials (e.g., polycarbonate panels)
• Looks trendy

Cons:

• Looks trendy
• Drainage from workshop roof would need to be diverted from the East side around to the West (probably gutters)
• West-facing clearstory windows may not provide much light, especially given forest to the West.
• Probably complicated flashing details where carport roof meets workshop siding

Out of these three, massing A seems to be the most promising, and is the one that I’ll explore in later articles. Of course, these are all just rough sketches — things could change once I start doing initial renderings.