Preparation

Timber Dochan

Resurrection of a unique surface preparation method and traditional wall fixing. The timber ‘Dochan’ quickly flattens out any uneven surface for a true, flat, vertical finish that holds together rather than disturbing old lime mortar and loose stone or brickwork.

 

Untitled

Remove the problem, vinyl paint, PVA, cement render and dirty, adulterated, poor quality Victorian black mortar. Drill hole between the bricks in a diamond pattern every three courses or equivalent if working in stone.

 

Untitled

With an axe, cleft timber Dochans from well seasoned temperate timber, essentially kindling. Using a wide chisel, adjust each one to fit the width of each hole whilst accentuate the twist a little. Then using a club hammer or lump hammer, tap each Dochan into the wall and listen for the pitch to change.

 

Untitled

The new line of the wall is marked out by stepping forward the window surrounds and repositioning the skirting boards. The original timber corner beads are refitted. A spirt level, plumb line or ideally a laser level carries this line over the Dochans marking out for a true flat level surface.

 

Untitled

The dochans are trimmed off in line or if necessary, a little artistic licence can be measured off the line to bring things like covering into line.

 

Untitled

It needn’t be this precise however inaccuracy accumulates and it’s easier to hang wallpapering on a true flat wall.

 

Victorian bay window

Details like this are not uncommon during renovation. Cutting to shape and mechanically fixing insulation board is impossibly difficult and will compromise the thermal performance. Casting Hemp and Lime using ‘Dochans’ easily tackles these problematic areas, any shape, level or thickness without compromising performance.

 

Methodology
Preparation
Resurrection of a unique surface preparation method and traditional wall fixing. The timber ‘Dochan’ quickly flattens out any uneven surface for a true, flat, vertical finish that holds together rather than disturbing old lime mortar and loose stone or brickwork.

Mixing
Revolutionary small scale hempcrete mixing process for safe clean material handling making domestic projects accessible and affordable. Measured and consistent mixing with the correct amount of water will prevent drying problem and improve performance.

Casting
The shuttering is secured to the Dochans and the Hemp and Lime cascades in. No stratified layers with a flat tamping tool, use a sharp stick to ‘poke it’ and knit it together. Quicker, easier, cheaper and more effective than building out with a lime plaster base coat

Results
No moisture build up, no correlation with internal humidity. Interstitial humidity follows external temperature. Relating to outside not in. Out performs u-value due to thermal inertia and hygroscopicity, no latent heat effect from condensation or evaporation. Hydrothermal passive heat recover from buffering the peaks of warm moist air?

 

Case Studies
Hemp Lime projects
The damp Victorian terrace, steamy hygroscopic bathroom and open plan emancipated kitchen, every home has cold spots.

Talks and workshops
Hemp Lime training
Renovation, conservation and new build construction. Preparation, mixing and casting onto existing masonry, infilling traditional timber frames and solid wall monolith construction.

Advice and consultancy
Hemp Lime preparation
Damp pathology, building principles, design critique, project planning and team building.

 

Bristol Hemp and Lime
Hygrothermal passive heat recovery, solves damp problems with the secondary effect of improving the thermal efficiency of older buildings.