Breathable membrane is always specified over traditional felt because it lets water vapour escape the roof void while blocking liquid water, preventing the condensation that rots battens and rafters. Traditional impermeable felt traps moisture, causing timber decay over 20-30 years. Breathable membrane has been Building Regulations standard since the early 2000s.
Breathable membrane in a roofing quote instead of felt is not a premium add-on — it is the current standard specification. Understanding why matters before accepting a quote that specifies traditional felt.
Bitumen felt under tiles acts as secondary waterproofing. The problem: it is impermeable. It traps moisture inside the roof void. Condensation from warm moist air rising from living spaces cannot escape. Over time, moisture accumulates in the roof void causing condensation on cold timbers, batten rot, and eventually the mould and timber degradation that appears as dark staining in the loft.
Breathable roofing membrane is microporous — pores large enough for water vapour molecules to pass through, too small for liquid water droplets to penetrate. Moisture from inside the house can migrate through the breathable membrane rather than being trapped. This keeps the roof void drier, extends batten and rafter lifespan, and reduces condensation-related damage.
Building Regulations Approved Document C requires roof coverings to resist moisture penetration, and breathable membrane underlay has been the standard specification for new pitched roofs since the early 2000s.
Source: Approved Document C, Building Regulations
All our re-roofs use breathable underlay. Free loft underlay check across Ashford and Kent.
Book Free SurveyYes, significantly. A re-roof using traditional felt installs a moisture-trapping system for the next 40–60 years. A re-roof using breathable membrane allows the roof to manage moisture correctly for the same period. The cost difference is typically £200–£400 on a standard semi-detached re-roof — modest relative to the total cost. A contractor quoting felt rather than breathable membrane is making a specification decision that affects roof performance for decades.
In the loft on a bright day: traditional bitumen felt appears as a dark, opaque layer. Breathable membrane appears lighter, often white or silver. If you can see significant light through it, the felt has perished — a finding that typically supports re-roofing rather than continued tile repair.
All our re-roofs specify breathable membrane as standard. Free survey.
Book Free SurveyEvery roof felt vs breathable membrane job starts with a free inspection and written quote before any work begins. We do not start work until you have confirmed the written quote. Our standard rates apply across Ashford and the surrounding Kent area.
We cover all Ashford postcodes and the surrounding towns: Folkestone, Canterbury, Maidstone, Tenterden, Hythe and the villages across the Weald. Emergency cover is available 24 hours a day on 01233 877 146.
No call-out fee across our full service area. Written quote before work starts. For roof felt vs breathable membrane work the quote is provided on the same visit as the inspection in most cases. You pay only for work carried out.
All re-roofing work and major repairs carry our written 10-year workmanship guarantee. Lead flashing work is guaranteed for 10 years. Minor tile repairs carry a 2-year guarantee. The guarantee is provided in writing at completion and transfers to a new owner if the property is sold.
We are registered with the National Federation of Roofing Contractors. Verify our registration at nfrc.co.uk. We carry 5m public liability insurance on every roof felt vs breathable membrane job. Insurance certificate available on request before work starts.
Ashford's housing stock spans five decades of construction: Victorian and Edwardian terraces in Newtown and the older town streets, 1930s semis in Kennington and Willesborough, post-war and 1960s estates at Bockhanger, Stanhope and Park Farm, and more recent development across the southern suburbs.
Each era presents different characteristics. Victorian clay tile on period properties requires matching reclaimed material and lime mortar at any repointing work. 1960s concrete interlocking tile on the estates is now 50-65 years old with corroded nail fixings on most unmodified properties. Understanding which housing era a property belongs to is the starting point for any assessment.
These estates are Ashford's highest-volume source of roofing work. The 1960s-70s concrete interlocking tile stock is now 50-65 years old. Nail sickness is present on the majority of unmodified properties. If you live in one of these areas and have not had roofing work in the last 15 years, a free assessment is worthwhile.
The Victorian terraces in Ashford's Newtown area and the older streets around the town centre require period-appropriate specification: reclaimed or reproduction clay tile, lime mortar at chimney repointing, and conservation-aware approach to any work on visible elevations.
Free survey and advice across Ashford and Kent. Call 01233 877 146.
Call 01233 877 146Impermeable felt underlay works against the roof's moisture management in two ways. First, it acts as a condensation surface: warm moist air rising from below meets the cold felt and deposits moisture. Second, it prevents that moisture from dissipating — water deposited on the felt surface can only evaporate back into the void or drain onto the batten. Batted that remain wet dry slowly. Over 20-30 years, the accumulation of condensation cycling softens and rots the timber.
Breathable membrane allows water vapour through while blocking liquid water. The moisture that would have condensed on traditional felt passes through the membrane and exits via eaves ventilation. The battens and rafters remain drier. Structural timber behind breathable membrane on a well-ventilated roof shows significantly less deterioration at comparable age than equivalent timber behind traditional felt.
On re-roofing projects where we strip 1970s-1980s roofs with original felt, batten condition varies considerably. Properties with adequate eaves ventilation and naturally ventilated loft spaces show less deterioration. Properties where soffits were replaced with solid uPVC in the 1990s — blocking the original ventilation gap — show significantly worse batten condition. The felt underlay and the blocked ventilation created the conditions for the deterioration we find.
Breathable membrane is most effective when combined with adequate eaves ventilation. The minimum is a continuous 25mm ventilation gap at eaves level on both sides of the roof. On properties where uPVC soffit replacement blocked the original ventilation gap, we reinstate ventilation as part of the re-roofing specification. This is not optional — it is part of correct current practice.
For context on how roofing costs compare across the range of work we carry out, here are realistic price ranges for the most common jobs across the Ashford area. All prices include labour and materials. VAT is not applicable on most domestic residential roofing work.
| Job Type | Typical Cost |
|---|---|
| Single tile replacement | £150 – £300 |
| Ridge repointing (per 4m) | £200 – £400 |
| Lead chimney flashing replacement | £500 – £1,100 |
| Full re-roof (3-bed semi, concrete tile) | £4,800 – £7,500 |
| Flat roof replacement (GRP, up to 20m2) | £900 – £1,800 |
| Full gutter clear (semi-detached) | £80 – £160 |
| Fascia and soffit replacement (semi) | £800 – £1,800 |
| Roof condition survey | £120 – £200 |
Free written quotes on all work. No call-out fee. Call 01233 877 146 to book.
We are a family-run roofing business based in Ashford, covering the town and the surrounding Kent area. We have been working on roofs in this area since 2003. Every job is carried out by our own employed team — we do not subcontract labour. The people who quote are the people who work.
We are registered with the National Federation of Roofing Contractors (NFRC). Our registration can be verified at nfrc.co.uk. We carry £5m public liability insurance on every job. Our insurance certificate is available on request before any work starts. All re-roofing work carries a written 10-year workmanship guarantee. Lead flashing work is guaranteed for 10 years. The guarantee is transferable to a new owner if the property is sold.
We cover Ashford and a broad area of the surrounding Kent countryside: Folkestone, Hythe, Canterbury, Maidstone, Tenterden, and the villages across the Weald and Romney Marsh. Emergency cover is available 24 hours a day, 7 days a week. Call 01233 877 146 for any roofing emergency. For non-urgent work, we aim to survey within 5-7 working days and have the quote in writing within 48 hours of the survey.
We do not charge for call-outs or surveys. Every job gets a written quote before a single tile is moved. The quoted price is the price on the invoice unless we identify and agree additional scope with you during the work. For re-roofing projects where deck condition is unknown before stripping, we include a clear provisional allowance for batten replacement rather than presenting you with a surprise on invoice.
These are the questions we are asked most frequently when homeowners call us for the first time. If your question is not here, call 01233 877 146 and we will answer it directly.
Yes. All call-outs and surveys are free of charge across Ashford and the surrounding Kent area. The written quote we provide after the survey is also free and carries no obligation. We do not charge for surveys even on properties where we ultimately recommend no immediate work.
For emergency calls where water is actively entering the building: same day where call volume permits. For the most urgent calls — active ingress, safety hazard from displaced tiles — we aim to attend within 2 hours. Out-of-hours emergency cover is available 24/7 on 01233 877 146. For non-urgent work we survey within 5-7 working days.
Written workmanship guarantee on all work. 10 years for full re-roofing and lead flashing work. 5 years for ridge repointing. 2 years for minor tile repairs. The guarantee is provided in writing at completion. It transfers to a new owner if the property is sold. We are NFRC registered and carry £5m public liability insurance.
For most standard concrete interlocking profiles we carry matching tiles on the van. For conservation area repairs requiring reclaimed clay tile or matched Welsh slate, we source from Kent and Sussex demolition salvage and confirm match quality before committing. We show samples on any repair where visual matching is important before starting work.
We cover Ashford and all of the surrounding Kent area: Folkestone, Hythe, Canterbury, Maidstone, Tenterden, and the villages across the Weald. If you are outside Ashford town, call us and we will confirm whether we cover your postcode. Most Kent postcodes within 25 miles of Ashford are in our standard service area.
Last reviewed: July 2026
Traditional felt is impermeable and traps moisture in the roof void, causing timber rot. Breathable membrane lets water vapour escape while blocking liquid water, keeping battens and rafters dry.
Breathable membrane underlay has been the standard specification for new pitched roofs since the early 2000s under Approved Document C of the Building Regulations.
From inside the loft, traditional felt appears dark, stiff and often granular; breathable membrane is lighter (white, silver or cream) and more flexible. Visible light through the underlay means it has perished.
Yes. Breathable membrane works best with a continuous 25mm eaves ventilation gap on both sides of the roof, allowing the vapour that passes through to exit the roof void.