Planning the build
Why build an extension?
Initial design sketches
On-line Building Regs
Meeting planners
 Meeting building control
 Planning the foundations
 Planning the floor slab
 Marking out the footings
 Damp proof course issues
 Possible drainage problems?

 Construction of the walls
 Proposed roof structure
Windows diary
 Window challenges
 Initial window plans
 Making the casements
 Making the frame
 Designing leaded lights
 Making leaded lights
 Assembling the window
 The little window

 The door frame
Demolition diary
 The demolition starts!
 The demolition continues
 Still more demolition

Foundations diary
 Foundation issues
 Drain issues
 Digging the foundations
 Rethinking foundations!
 Pouring the foundations

Floor slab diary
 Rethinking the slab!
 Floor vent extensions
 Preparing the slab #1
 Preparing the slab #2
 Pouring the slab

Walls diary
 Preparing to build walls
 Build up to the DPC
 Build the walls #1
 Build the walls #2
 The gas men cometh
 Build the walls #3
 Finishing the walls
Roof diary
 Roof structure build
 Tiling the roof
 Finishing the roof
 Finishing the gables
 Roof insulation

 Floor screed
 Shower room
 Shower room floors
 Shower room walls
 Utility room
 Utility room walls
 Utility room floor
 Finishing the windows

Project finished!
 Final inspection
 The certificate
 Final thoughts

 Twelve months on!
 Material costs
Sister sites
 House re-roof project
 Home gas usage data

 Stop paint flaking
 DIY secondary glazing


Damp proof course (DPC) issues

The extension will straddle two parts of my house. the left-hand-side bit was built in the 1800s and the right-hand side in the 1930s. Initial inspection seems to show that the DPC level lies at a lower level in the new part to the old part. As I definitely want an internal floor without a step I will have to see what impact this might have.

The 'DPC' in the old part of the house behind the external toilet.

Actually, the old part of the house does not have a DPC as is seen in modern homes. The DPC was formed by pouring pitch over the wall which you can see running down the wall. It is also quite high on this side of the house.

It's interesting to note that the outside toilet's DPC (if there is one) is below the one in the main house wall!

The 'DPC' in the old part of the house in font of the toilet

Assuming the DPC runs around the house at the same level it can be assumed to be at this level here, although the air brick is above the DPC on the further side of the house. I'll need to knock away some the render to see the true situation.

The DPC in the 'new' part of the house is a traditional DPC but seems to be a couple of bricks higher than the old house. Where the level changes is currently hidden under the render.

'Tanking' the damp proof membrane to compensate for
different heights of the DPC

A difference in height between the old house and the new extension means that the damp proof membrane needs to extended height up the existing house wall and keyed into the DPC of the existing house at a higher level and covered by plaster.

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