Question 1

When is replacement preferable to chemical treatment?

Accepted Answer

If the cross-section of a load-bearing beam has been reduced by more than 25 %, or if there is any visible deflection (sagging), chemical treatment alone is no longer safe. Treatment will kill the infestation but cannot restore lost structural capacity. In those cases we either sister-joint a new matched member alongside the existing beam or replace it entirely, depending on the beam's heritage value and the conservation officer's preference.

Question 2

Will I lose the heritage character of my beams?

Accepted Answer

Not if the work is done well. Sister-jointing is our default approach precisely because it preserves the original beam in situ alongside a new matched member. Where replacement is unavoidable we source matched species (Irish oak for Irish oak, Baltic pine for Baltic pine), match the grain direction and reproduce any chamfers, stop-chamfers or decorative profiles. Most clients tell us they cannot identify the replaced members a week after handover.

Question 3

Do I need planning permission for structural replacement?

Accepted Answer

For domestic dwellings, no — like-for-like structural repair is exempt under the Planning and Development Act. For protected structures or buildings in an Architectural Conservation Area, you will need Declaration or Section 5 consent. We prepare the documentation, photographs and method statements required by the conservation officer at no extra cost and can liaise with the council on your behalf.

Question 4

What guarantees come with replacement work?

Accepted Answer

All new timber carries the supplier's manufacturer warranty (typically 25–30 years against latent defects). Our workmanship is guaranteed for the lifetime of the timber — meaning if a joint we made fails, we return and repair it at no charge. Where a structural engineer has signed off load calculations, that report transfers with the property and is often requested by future buyers' surveyors.

Question 5

Is replacement covered by Irish home insurance?

Accepted Answer

Often yes, where the cause was sudden (e.g. a slate that came off in a storm and led to wet rot) and the property had been properly maintained. Long-term gradual decay is usually excluded. We provide detailed loss-adjuster-friendly reports on request, including dated photographs and a written opinion on probable cause.

Question 6

Can you replace timber lintels above windows and doors?

Accepted Answer

Yes — and we do this regularly in older Carlow, Wexford and Kilkenny terraces where the original oak lintel has decayed. The work involves temporary needle-propping above the opening, careful removal of the failed lintel, insertion of a new matched member, repointing the brick or stonework and replastering. A typical lintel job takes 1–2 days and is much less disruptive than most homeowners fear.

Question 7

Do you work alongside other trades?

Accepted Answer

Always — most replacement jobs touch electrical wiring, plumbing or insulation. Our project manager coordinates with your existing electrician and plumber, or we can supply our own approved trades. We are fully insured (€6.5m public liability) and operate to the Construction Industry Federation standards.

Question 8

How is replacement timber treated to prevent future woodworm?

Accepted Answer

Every piece of replacement timber that leaves our workshop has been pre-treated with boron in a dip tank — meaning the boron is fully diffused through the cross-section before installation. This gives the new member the same long-term protection as our standard surface treatment programme, with the boron already in the heart of the wood.

Question 9

Is sister-jointing as strong as full replacement?

Accepted Answer

Yes, when done properly. A correctly designed sister-joint transfers load through a new matched member running alongside the original, with the joint engineered to the same allowable stress as the original beam. A chartered structural engineer signs off the calculations on every job. Conservation officers actually prefer sister-jointing because it preserves the original timber in situ as a witness to the building's history.

Question 10

Do I need permission to replace structural timber in a listed building?

Accepted Answer

Yes — Section 5 Declaration or a Declaration of Exempted Development from the local authority's conservation officer. We prepare the photographs, method statement and reversibility note required, liaise with the council on your behalf, and absorb the cost as part of the contract. Lead time for consent is typically 4–8 weeks.

Question 11

How long does the new timber last?

Accepted Answer

Irish-grown oak, properly air-dried and boron-treated, has a structural design life of 200+ years in a maintained building. The manufacturer warranty on our replacement timber is 25–30 years against latent defects; our workmanship guarantee is for the lifetime of the timber.

Question 12

Can replacement work be combined with other treatments?

Accepted Answer

Almost always — and it usually should be. A beam that needed sister-jointing because of wet rot usually sits in a roof or floor that needs damp investigation, and the surrounding timber often needs boron treatment to prevent recurrence. We coordinate the whole programme so trades aren't tripping over each other.

Sensitive Structural Timber Replacement

Three approaches, one principle

Sister-joint

Splice & scarf

Full like-for-like

When treatment alone is no longer enough

Wrong replacement is worse than no replacement

When to call us instead of a chemical specialist

Visible beam deflection

Cracking in walls above

Door or window frame distortion

Soft, spongy timber on probing

Visible rot mycelium

Post-leak floor sag

From quote to handover pack

Structural quote + engineer sign-off

Conservation officer engagement

Workshop preparation

Temporary propping

Joint making

Finish and document

Lifetime workmanship guarantee

Three first-floor joists sister-jointed in matched oak

Why Enviroteck for structural replacement

Irish-grown oak, air-dried 24 months

Five matched timber tones held in stock

Lifetime workmanship guarantee

Engineer + conservation officer panel

Most-requested counties for replacement

Also serving across Leinster

Where our joinery team works most often

Pair replacement with

Low-Pressure Injection Treatment

Dry Rot & Wet Rot Treatment

Damp & Rising Damp Quote

Twelve answers from the carpentry studio

Speak to a replacement specialist

Request your free quote