House Extension System

Dry Fix extensions need no wet trades

Add quality space to your home using only basic DIY skills

Dry Fix extensions are complete, foundation up self-build kits utilising build systems found on the latest high specification eco-homes. Specifically engineered for simplified construction, our extensions can be completed without the need for additional trades like bricklayers, plasterers or roofers. Yet, they still deliver a quality of finish and comfort that far exceeds the vast majority of traditionally constructed extensions.

Internal Construction of Fir Tree Cottage Eco Home

Fir Tree Cottage is a £1.5m, 5 bedroom, 5 bathroom eco-home we're building using the same technology as in our Dry Fix extension kits

  • A complete extension – from foundation up to finished roof and including sliding-folding doors
  • Constructed using proven, warrantied and BBA-approved technology that’s the last word in energy efficiency and comfort
  • No block or bricklaying required at any stage (even foundations)
  • If you can nail, screw and glue, dig, plus mix and pour concrete, you can build your Dry Fix extension
  • No wet plastering. Only competent decorating skills required to finish
  • Engineered construction incorporating certified best building products from across Europe
  • Highly insulated, air-tight and energy efficient additional space, plus an eco-friendly form of construction
  • Contemporary design and finish that transforms the look of your home
  • ‘Dry’ construction means no drying out, no cracking and you can decorate and use the space sooner
  • Unique construction detailing that manages normal ‘movement’, obviates snagging typical on traditional builds
  • Choose from render, pebble dash or contemporary timber clad finish

The DIY build with the “Grand Design” finish

Self-building shouldn’t mean having to compromise on finish, quality and style. When building your Dry Fix extension you won’t be. Our self build kits bring together the best materials (including several European products your average British builder won’t even have heard of), clever engineering and smart detailing. Our aesthetic looks amazing, but was purposefully designed to be easy for you to achieve.

Larch with detailing

Larch detailing around window

Siberian larch cladding

Siberian larch cladding choice

Parapet roof detailing

Parapet roof detailing

  • The Dry Fix difference…
  • No cheap, hollow-sounding plasterboard stud walls
  • Extra strong final wall lining feels solid and stands up to wear and tear
  • Unique detailing hides any movement cracks that typically occur at floor, ceiling and wall junctions in traditional builds
  • Easy fill, sand and decorate finish. No need for special skills
  • No drying out, no condensation, no delay to floor finishes or decoration
  • Insulated to easily exceed current building regulations
  • Highly airtight and draft proof, meaning even less heat loss
  • Sound-proof, "fully closed" construction
  • This engineered build system is twice as strong as traditional masonry and five times stronger than standard timber frame
  • Choice of contemporary external render and timber clad finishes
  • No brick outer leaf or slips required
Shadow gap at floor level

Shadow gap at floor-wall junction

Shadow gap at ceiling level

Shadow gap at wall to ceiling

Secret gutter roofline detailing

Eaves / roofline detailing

Greater comfort, lower bills, exemplary green credentials

The trouble with masonry builds…

Bad cavity fill wall

Would you bet your heating bills on this? A real-world example of cavity fill, courtesy of Kingspan.

What is traditional cavity wall construction’s dirty secret? Easy – it works better in theory than in practice! Builders fail to install the batts or boards to the specification used in the U-value calculations. This means the wall can’t hope to deliver the promised energy efficiency. This report by Kingspan surveyed the problems on real building sites in England. The trouble with masonry cavity insulation:-

  • Gaps allow convection between the inner and outer leaf of the wall, circumventing the insulation
  • Cold (and damp!) bridging from “Wets” (mortar) falling between the leaves onto the insulation during bricklaying
  • Permanently damp insulation will not perform to its theoretical efficiency (just 1% water by volume reduces mineral fibre insulation’s effectiveness by 75%)
  • Insulation is absent – shortages are bricked over to prevent holding up work

Build yourself comfortable, efficient, additional space

A Dry Fix extension delivers on promised U-values and energy efficiency. Its insulation effectiveness is almost entirely assured in the factory. Our structural insulated panels feature captive, continuous urethane ‘foam’ insulation. The insulation auto-adhesively bonds to the carrier boards, sealing and creating a structural join. As long as erectors follow the correct (and easy) jointing procedure using gun foam and silicone, high levels of airtightness are a certainty. The Dry Fix system will comfortably achieve air leakage of less than 1 cubic metre of air per square meter of floor space per hour at 50 pa (elevated) pressure; Part L of the Building Regulations permits 10 times as much.

Why airtightness really matters in energy efficiency

  • Insulation only works when the heat must pass through it to escape
  • Poor airtightness will allow warm air to bypass insulation
  • Convection currents from warm to cold air create a ‘draw’ effect – just like a chimney
  • Warm air is exhausted out of the building, dragging cold air in!
  • A continuous vertical 1mm gap in airtightness in a 1m wide wall can reduce insulation effectiveness by 79% – Measurement carried out by Institut für Bauphysik, Stuttgart; Source: DBZ 12/89, pp 1639
Effect of airtightness on insulation

Small gaps in the building fabric can have a big impact on insulation

Exceeds Part L target u-values by 25% – minimum

Dry Fix targets future energy efficiency demands, rather than begrudgingly meeting current regulations. That’s why our basic system exceeds Building Regs by at least 25%. Those with an appetite for even greater long-term savings, can upgrade to Code 6 / PassivHaus levels at over 50% better than current requirements. Larger glazed areas are permissable also when udgrading insulation. We design your kit to achieve the right balance on construction elements for your specific build.

Eco-friendly building with zero ozone depletion and minimal carbon emissions

Dry Fix combines eco-friendly solutions with responsible sourcing to minimise the environmental impact of your build. All insulation and any blowing agents used are certified zero ozone depletion. All timber is FSC certified or covered as part of PEFC Chain of Custody certification. The wall and roof construction elements have BRE Green Guide element ratings of A to A+. And, don’t forget how incredibly energy efficiency your extra space will be in everyday use.

Get more space out of your extra space

Get at least 1 square metre extra usable space

When it comes to planning permission, your local council is only interested in the external dimensions of your extension. So, why waste space on bulky cavity walls, Dry Fix provides 120mm extra habitable space all around your room for the same size extension.

  • At 9.85m2 versus 8.79m2 for cavity masonry, you can enjoy an extra 1 square metre of usable space in a 3m deep x 4m wide abutted extension
  • Get 1.55m2 extra interior space in a 4m deep x 6m wide abutted (eg rear) extension
Dry Fix self build brochure

Build options to suit your abilities and budget

We have three build levels. Choose the one that best suits your budget and confidence in completing the necessary works. Detailed descriptions of the stages and skills required are available upon request.

Name External Dims. Self Build Kit Build Assemble Build
Full kit, some cutting required Fully dimensioned kit, no cutting Part assembled kit, no cutting
See below for more details of build options
Semi 4m (w) x 3m (d) £8750 £9395 £9850
Detached 4m (w) x 4m (d) £11095 £11895 £12495
Luxury 5m (w) x 4m (d) £12595 £13495 £14195
Our prices include sliding-folding doors

Build levels explained

"Self Build" contains a full bill of materials with which to construct your extension. The structure is fully dimensioned, ready for assembly. The lining, cladding and insulation materials will require cutting to fit.

"Kit Build" is a full bill of materials that require no cutting. Every major component is dimensioned ready for fitting, including the lining, cladding and insulation materials.

"Assemble Build" Assemble Build is a full bill of materials with every major component dimensioned, plus partial pre-assembly in our factory into fewer, larger components.

Our kits include materials for standard trench-fill foundations. Your Building Control Officer may have specific requirements for your foundation design, depending upon your site. In the event of this, we can customise your kit accordingly. This may incur an extra charge.

You could build a Dry Fix extension this Summer!

Contact us for more information on building your Dry Fix extension or for an order form

Dry Fix is the extension you can build yourself