Glulam vs solid timber: what to choose for a house by the sea

From the outside, glulam and solid profiled timber walls look alike: both are planed to size and assembled with an interlocking profile. The difference is in what each log is made from. Glulam (glued laminated timber) is glued together from several dried layers, while solid profiled timber is cut from a single trunk and comes either undried or kiln-dried. In Adjara the glulam vs solid timber choice comes down to exactly this, because it decides how much the house will settle and crack.

Settling in a humid climate

Wood gives off or takes up water until its moisture content balances with the air. In Batumi the air is damp for most of the year, so undried timber dries more slowly here than in a dry climate, and the settling drags on. This kind of timber is a poor fit for the coast: the wall takes a long time to settle, and the finishing and the windows have to wait.

Glulam arrives from the factory dry and hardly settles, but in Batumi's humid air it takes up a little water and swells, so it also needs gaps around windows and doors. Kiln-dried solid timber settles noticeably less than undried timber but more than glulam, so its openings are given a larger settling allowance.

Cracks and shape

Solid timber cracks as it dries, because the stress inside the trunk is released as splits along the grain. In solid profiled timber these can be deep and wide, and on the facade wind-driven rain runs into them. Glulam is made from layers with the growth rings running in different directions, so it holds its shape and cracks rarely, and not deeply.

On a wall by the sea, cracks are more dangerous than they look. Each one gives water a path to the core of the log, so it has to be filled and painted over.

Seismic load, spans and large windows

Both types of timber make a light house, and the seismic load on it is small. The courses are tied together vertically with dowels and the house is anchored to the foundation as the calculation requires. The structural engineer checks the corners and the wall sections between large windows separately.

Glulam comes in longer lengths and larger sections, and it is used for beams over wide spans and for walls with panoramic windows. Solid timber is limited by the size of the trunk, so long walls are assembled with joints, and every joint on the facade is one more place where water and wind get in.

Glue and damp: the risk with glulam

The weak point of glulam is the glue line. If the wrong glue is used or the gluing process is not followed, the line can open up in a damp climate, and the layers on the facade come apart. We ask the manufacturer which glue was used, which standard the timber was glued to and whether it is approved for external walls, and we look at the log ends in the batch.

Solid timber needs no glue, so it cannot delaminate. Its weak points are different: cracks, blue stain and rot if the timber arrives wet and is stacked in the rain without spacers.

Glulam vs solid timber: build time and the season

A glulam kit is made at the factory to the design, and the walls go up quickly. We confirm the production time with the factory before the contract is signed, because it decides whether the house can be closed in before autumn. Long, heavy beams are lifted by crane, and we check the access for it in advance.

Solid timber can be put up by a small crew, but after assembly it needs a break for settling. Both kinds of wall must get a protective finish before autumn: in Batumi more than half of the year's rain falls between September and January, and bare timber in the rain turns grey and cracks faster.

A rental house and checks from abroad

For a house managed from far away, predictability matters. Glulam moves less, and after the first winter the doors and windows need adjusting less often. With solid timber the joints have to be tightened and caulked in the first years, and you need someone on the spot to do it.

If you are not in Batumi, ask for these in the reports: moisture meter readings on the timber when the batch is accepted, and photos of the insulation between the logs and of the damp-proof course on the plinth under the bottom row of logs. These places are hidden later, and they decide how soon the house will need repairs.