The Bleeding Wood: Why Cheap Cedar Cladding Turns Black
Paid extra for a cedar garden room? Discover why cheap galvanised nails cause permanent black rust stains, and why stainless steel fixings are non-negotiable.
People love western red cedar. They drop serious extra cash to upgrade the outside of their new garden studio. It looks brilliant on day one.
Six months later, the whole building looks terrible. The rich colour is gone, and the boards are covered in streaky, black tear marks running down the wood.
The customer thinks the timber is rotting. It isn't. The cheap builder who put it up just ruined it by using the wrong nails.
The Iron Reaction
Cedar is packed with natural oils and acids. That is what stops it from rotting. But those same oils hate iron.
When a cowboy builder fires a standard, cheap galvanised nail into a cedar board, it’s a ticking time bomb. The second the heavy Dorset rain hits that wall, water gets into the nail hole. The iron in the cheap nail chemically reacts with the acid in the wood.
It creates a dark black stain that literally bleeds down the face of the cladding. You get black stains on cladding trailing under every single fixing. You cannot wash it off. You cannot sand it out. The timber is permanently ruined.
The Coastal Fade
Then you have the sun. The weather down here on the coast is brutal on a garden studio exterior.
If you just leave raw cedar out in the elements, the UV rays cook it. The sun strips the natural colour right out of the wood and turns it a dull, patchy silver. Some landscapers will tell you they are letting it "weather naturally" to save themselves a job. I call it looking neglected.
Stainless Steel and Oil
When we build a cedar cladding garden room, we don't cut corners on the finish.
We absolutely refuse to use standard nails. We load our nail guns strictly with marine-grade stainless steel pins. There is zero iron in them. No iron means no chemical reaction, and absolutely no black rust stains down your expensive timber.
We also don't leave the wood raw. Before the British weather can even touch it, we coat the entire building in a proper timber treatment. Dorset sun requires heavy-duty UV protection wood oil. It chemically locks the rich, warm colour into the timber and repels the rainwater.
If you are paying for premium cedar, make sure your builder knows how to actually fix it to the wall.
Pop down and see the lads at 78 Alma Rd, Bournemouth BH9 1AN, UK, or ring the site phone on 07835 390845. Come and see what properly treated timber looks like.
