Upgrading Your Garden Room Roof: Felt vs. EPDM Rubber

An outbuilding roof still needs a sound deck, adequate fall, secure edges and reliable drainage. The right specification depends on whether the space is unheated storage, a workshop or a year-round occupied room. This guide explains the practical checks a Bromley property owner should make before requesting or approving work.

Quick answer

An outbuilding roof still needs a sound deck, adequate fall, secure edges and reliable drainage. The right specification depends on whether the space is unheated storage, a workshop or a year-round occupied room.

EPDM in this decision

EPDM is a flexible sheet membrane. Large areas can have few field joints, but edges, outlets, corners, adhesives and penetrations still require careful preparation and detailing.

Reinforced roofing felt in this decision

Modern reinforced felt is normally installed as a layered system. Deck preparation, bonded laps, upstands, edge details and safe hot-work planning all affect the result.

A practical comparison

EPDM

EPDM is a flexible sheet membrane. Large areas can have few field joints, but edges, outlets, corners, adhesives and penetrations still require careful preparation and detailing.

• Flexible sheet membrane
• Can cover simple areas with few field joints
• Corners, outlets and adhesives remain critical

Reinforced roofing felt

Modern reinforced felt is normally installed as a layered system. Deck preparation, bonded laps, upstands, edge details and safe hot-work planning all affect the result.

• Multi-layer reinforced membrane
• Adaptable around many traditional flat-roof details
• Installation method and hot-work controls must be agreed

How to choose between them

Compare suitability for the actual roof rather than selecting from a generic ranking. Pitch, deck, weight, drainage, visible character, access, detailing and the installer’s relevant experience should drive the choice.

The main decision this article should support

EPDM is a flexible sheet membrane. Large areas can have few field joints, but edges, outlets, corners, adhesives and penetrations still require careful preparation and detailing. Modern reinforced felt is normally installed as a layered system. Deck preparation, bonded laps, upstands, edge details and safe hot-work planning all affect the result.

• Deck condition, span and structural support
• Roof fall and direction of drainage
• Edge trims, eaves and abutments
• How will the building be used?
• Is the existing deck dry and structurally sound?

What should be inspected?

• Deck condition, span and structural support
• Roof fall and direction of drainage
• Edge trims, eaves and abutments
• Insulation, vapour control and ventilation for occupied rooms
• Wind uplift at exposed edges
• Whether old sheets could contain asbestos or be fragile

Access can change the repair method

Terraced and converted properties can have different access at the front and rear. The quotation should say whether scaffold, a tower or another planned system is assumed, and how materials and waste will move without damaging occupied areas.

• Front and rear access considered separately
• Shared routes agreed before work
• Protection below the work included
• Parking and delivery assumptions recorded

Decide whether the outbuilding is simple storage or occupied year-round. That changes the need for insulation, vapour control, ventilation, robust finishes and internal comfort.

Weather can stop otherwise simple work

Wind, lightning, ice and heavy rain can make access or uncovered roofs unsafe. A realistic contractor will postpone work or use temporary measures when conditions do not support the agreed safe system. The HSE roof-work guidance explains the main requirements and hazards.

Questions to ask in the quotation

• How will the building be used?
• Is the existing deck dry and structurally sound?
• What insulation and condensation strategy is proposed?
• Can the roof be accessed and maintained safely?

Related local service

For property-specific advice, see Flat roofing in Bromley. The service page explains inspection, access and quotation arrangements.

Frequently asked questions

How should guarantees be compared?

Compare the exact work covered, duration, exclusions, maintenance duties and who stands behind the guarantee. A guarantee cannot compensate for an unsuitable specification.

Should I obtain more than one quotation?

For substantial work, comparable written quotations can help. Make sure contractors price the same scope rather than comparing totals with different omissions.

Should the quote include waste and protection?

Yes. Ask it to identify access, protection, preparation, disposal, materials, exclusions and work that can only be confirmed after opening the roof.

Discuss your roof with a local roofer

For an inspection and written quotation in Bromley, call 020 3886 3911 or email yourbromleyroofers@gmail.com. Describe the property, the roof area and any visible leak or damage. Photographs taken safely from ground level or inside the loft can also help.