Douglas Fir Beams & Posts

Douglas Fir Timber Beams for Sale in Ireland

Douglas Fir is the softwood of choice for exposed beams and posts: strong for its weight, straight grained and warm in colour. Our Douglas Fir beams and posts are sawn, stocked in our warehouse and delivered across Ireland.

Douglas Fir Beam and Post Sizes

Choose the section by the job, then the length by the span.

• The 90×90 mm post is for pergola and carport posts, fence and gate posts, and handrail posts.
• The 150×150 mm (6×6 inch) beam is the all rounder for porch posts, pergola beams, canopies and exposed ceiling beams. Where you can, choose a length that spans a garage opening or pergola in one piece, with no joint to support.
• The 200×200 mm (8×8 inch) beam is the heavy section for main beams, timber frames and feature beams that need to look substantial.

For any beam that carries a structural load, have an engineer confirm the section for your span.

Why Choose Douglas Fir Timber

• Strength to weight: at around 530 kg/m³ it is strong and stiff but much lighter to lift than oak.
• Straight grain: long, clean sections that stay true, which is why it’s used for exposed structures.
• Colour: a warm reddish pink that mellows to a honey tone.
• Durability Class 3: natural resin adds weather resistance, with a service life of 15 to 25 years outdoors when finished and detailed well.

Douglas Fir or Oak Beams?

Oak beams and posts are denser and more durable outdoors, with a traditional look. Douglas Fir is lighter, straighter and easier to handle and fix, and its warmer colour suits contemporary pergolas, porches and interiors.

Using Douglas Fir Outdoors

• Stand posts on a stainless steel post base above the ground rather than burying them, so the end grain can dry.
• Seal cut ends and the tops of posts.
• Use stainless steel or galvanised bolts and brackets from our outdoor timber hardware.

Oiling Douglas Fir

Outdoors, Douglas Fir lasts longest with a finish. Left bare, it weathers to silver grey. Most people oil or stain it within the first few months to protect it and keep the warm colour, then refresh it every two or three years. See our wood oils and stains.

For every post and beam we stock, browse all our timber posts and beams.