Find here technical information on the construction of our timber frame kit homes for self-build

We use two types of wood; spruce (Picea abies) for the structure and for external applications. Pine (Pinus sylvestris) or spruce is used for the internal fittings. Pine wood has a warmer colour than spruce, if left natural. Wood from Lapland has tight annual growth rings, thus it is very strong and naturally rot resistant. With the exception of the ground sill, which is pressure impregnated class 3, all other wood is natural.

All the wood has been kiln dried, planed and profiled to precise measurements. The structural wood has been verified, stress graded and marked. Planed smooth wood is easy to handle and makes the fitting of insulation simple. External wood is only planed on three sides. The fourth side, facing out, has been purposely left with a fine re-sawn surface for optimal paint adherence.

In order to minimize thermal bridging of the foundations, TIRO recommends the following procedures as designed here below:
Solid concrete slab
Concrete floor on a crawl space
Foundations for a floor joist framing.

IMPORTANT: In every case, the floor must be as well insulated as the walls, in order to guarantee the good comfort of the house.

The external wall structure is made of 45×195 mm (1.77×7.7”) studs, with a spacing of 0.60 m (23.64”) centres. The external stud walls are pre-assembled in multiples of 0.60 m (1.80, 2.40, 3.00 m etc.). On the inside of the external walls, 45×70 mm studs are fixed horizontally, creating an insulated space suitable for the fitting of plumbing and electrical cables. This design, as well as being very strong, allows for 265 mm thick insulation; R= 7.01, U=0.142 (thermal calculation). The insulation is not provided with the kit. We recommend ROCKWOOL, semi-rigid panels.

Horizontal composition of external walls: External boarding 22×145 mm + nailing battens 22×45 mm + ASFABOARD wind protection 12 mm + studs 45×195 mm + OSB-board 11 mm + PE vapour barrier + horizontal studs 45×70 mm + inner lining (not provided). Total wall thickness (inner lining not included): 332 mm (13.08”).

Vertical composition of external walls: Damp proof course + ground sill 45 mm + wall plate 45 mm + stud 2 390 mm + top plate 45 mm. Total wall height: 2 525 mm (99.485 ”).

The external cladding is made of 22×145 mm rebated boarding, with the re-sawn visible side facing out. It can be positioned horizontally or vertically. The external boarding, as well as all other external wood, must be painted.

Asfaboard (UK: Hunton Bitrock) is the Nordic generic name for a bitumen impregnated fibreboard wind protection. See: It is made of wood fibres and asphalt. This board is light, easy to handle and has an excellent vapour permeability, as well as being an acoustic insulator. At the joints, water-tightness is assured by an adhesive strip. The Scandinavians have used it for many decades. It is nailed on the outside of the external wall structure and also covers the openings for doors and windows. Therefore, the interior is quickly protected from wind and rain. The openings are cut out when the doors and windows are ready to be installed.

Doors and windows can be positioned without restrictions, if not wider than 2.40 m or taller than 2.24 m. The doors and windows must be positioned so that all the top lintels are aligned. All doors and windows reaching the floor, should have the same height. We recommend a fitting flush with the exterior cladding.

The partition wall structure of 45×70 mm (1.77×2.76”) studs, can be included as an option and is priced per linear metre of partition wall. It is not pre-assembled. For insulation we recommend ROCKWOOL semi-rigid panels. The insulation is not provided with the kit.

A 1-floored house has a standard roof pitch of 30°, but could be ordered with a lower pitch. The roof trusses (A-frames; with vertical struts on the rafters) are spaced at 1.20 m (47.28”) centres. Space is provided for 300 and 400 mm insulation of ceiling (11.82” to 15.76”). We recommend ROCKWOOL semi-rigid panels. The insulation is not provided with the kit.

A 1½ – floored house has a roof pitch of 45°. The roof trusses (A-frames; with vertical struts on the rafters) are spaced at 1.20 m (47.28“) centres. There is an intermediate beam between the trusses, of the same dimensions as the ceiling joists (42×360 mm, 1.65×14.2”) and parallel to these. Between the rafters there is space for 290 + 70 = 360 mm of insulation (14.18”). We recommend ROCKWOOL semi-rigid panels. The insulation is not provided with the kit.

All roof-trusses carry the load from one external wall to the other. No load-bearing interior wall is required as support. Thus rooms can be positioned and repositioned at buyer’s choice without restrictions.

The erection of the roof trusses on a 1-floored house can be carried out by a telescopic forklift with driver (half a day), at the client’s cost.

For the erection of roof trusses on a 1½ – floored house, a mobile crane and its professional driver is required and to be paid for by the customer (half a day’s hire). The length of the crane’s arm must be a minimum of 25 m ( 80‘).

The kit contains a sarking (roof boarding) of 22×120 mm tongued and grooved board with sawn face, for a strong and well braced roof construction. The sarking also provides support for the roof-felt. The roof-felt is not included in the kit.

Floor boards (22×120 mm) are provided for the attics, not to be confused with the first floor flooring. Floor boards ( 28×120 mm) for the first floor can be provided as an option.

Customers are invited to visit our building sites.