Case Study: Timber Frame Extension in Tilehurst, Reading
Updated: Sep 2
This project is a narrow side return in Tilehurst, and narrow is exactly where timber frame earns its keep. We are recording each stage of the build here as it happens, starting with the demolition and the groundworks.
Why timber frame on a narrow plot
The walls do the work. A timber frame extension reaches the same structural performance and insulation values through a thinner wall build-up than brick and block, so more of the footprint ends up as floor you can stand on. On our projects that difference works out at around 20% more internal space.
On a large rear extension you might not notice it. On a side return like this one, where the whole width is a couple of metres, it is the difference between a usable room and a corridor.
Week one: demolition, footings and frame
The existing setup was a concrete driveway running down the side of the house with an old timber carport over the top. Both had to come out before anything could start.
Breaking out and removing the existing concrete driveway
Taking down the old timber carport and its corrugated roof
Digging the footings to the depth set out in the drawings
Building control inspection and sign-off on the open trenches
Pouring the concrete footings
Brickwork up to damp proof course, with the DPC laid over
Standing the timber frame walls and setting the roof joists
All of that inside five days, with the frame up and the roof structure on by the Friday afternoon.
The footings inspection
Nothing gets covered up before building control has seen it. The trenches were dug, inspected and passed before a single load of concrete went in. Foundations are one of the fixed inspection stages, and once the concrete is down, the only way back is opening it up again.
Building regulations approval is separate from planning permission, and the two run on their own timelines. Both matter, and the right one needs to be in place before work starts.
The footings themselves are no different for timber frame than for masonry. It is a common assumption that a lighter structure means a lighter dig, and it does not work that way, which we covered in more detail in our post on whether a timber frame extension needs foundations.
Getting the frame standing in the same week
The programme moves this quickly because the frame arrives cut and ready. Once the brickwork reached DPC and the sole plate was fixed down, the wall panels went up in sequence and the roof joists followed.
Speed on site matters more than people expect on a job like this. The house is occupied throughout, access is a single narrow route past the front of the property, and every extra week is another week of a skip on the drive.
Week three: outside nearly weathertight
By the end of week three the outside of the extension is close to complete. The shell is watertight and it is starting to read as a finished room rather than a frame.
Slip bricks fixed to the outer face, blending the extension into the existing brickwork
EPDM rubber membrane laid to the flat roof
Lead flashing dressed in where the extension meets the main wall
A tiled pitched section to the front, added to satisfy the planning conditions
French doors fitted
Slip bricks fitted on timber frame extension slip bricks fitted on timber frame extension slip bricks fitted on timber frame extension
The slip bricks are worth a word. Rather than a full brick outer leaf, a timber frame takes a thin brick slip bonded to the face, which gives the look of traditional brickwork without the wall thickness that would eat into the internal space. Matching the buff and dark tones of the existing house was the priority here, so the new work does not stand out as an obvious add-on.
The flat section is finished in EPDM, a single-piece rubber membrane that suits the low pitch and gives a long service life with no seams to fail. Where the roof pitches up at the front to meet the planning requirement, it is tiled to match the main house instead.
The finished extension
Five weeks from breaking out the old driveway to a finished room, and extension is finished.
Inside, the extension is plastered, decorated and floored, with recessed spotlights, roof lights bringing daylight into the middle of the room, and a radiator on the heating system. The narrow plot that made timber frame the right call from the start is exactly why the finished room works: the thinner walls gave the customer around 20% more usable floor than a brick, cavity and block wall would have, at the same U-value, so none of the width was lost to the wall build-up.
The roof is flat, finished in EPDM, but the front pitch is tiled to match the main house. That tiled section is there purely for appearance, at the planning stage the council asked for it so the extension sits comfortably against the original roofline rather than reading as a flat-roofed box bolted on the side.
The result is a bright, insulated room that looks like it was always part of the house, on a footprint most people would have written off as too narrow to bother with. If you are weighing up a timber frame extension on an awkward or tight plot, this is the kind of thing it makes possible.
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