Do Posi-Joists Need to be Treated?

There is no requirement to treat Posi-Joists unless you live within the area on this map, in which case a pesticide is applied before manufacture. It's required due to the infestation of the House Longhorn Beetle—a wood boring insect that loves to destroy your lovely trusses & joists (but for some reason only around the Woking area).

Posi-Joists are not tanalised, as they aren't designed to be exposed to the elements. If you aren't in the area that requires the pesticide treatment, you can still opt to have it carried out at an approx. 10% surcharge. But, please keep in mind that this isn't the same treatment as you'd find on timber at a builders merchant.