ROOF-EAVES-01
Tier 0 — Preview
Eaves detail — cold roof
Masonry cavity wall — natural slate — insulation at ceiling — cold roof ventilated
⚠ 2 structural requirements on this detail
ROOF-EAVES-01
Eaves detail — cold roof
Cold roofNatural slateBS 55342 SE requirements
⚠ Example detail only — confirm all specifications with a structural engineer before construction. Do not scale from this drawing.
Build-up layers
1
Natural slate tile
BS 5534 Part 1 — nailed to treated battens at correct gauge
2
Treated timber battens
Gauge per BS 5534 and pitch — size to SE/manufacturer spec
3
Breathable high resistance underlay
Wide overlay band at ridge — draped to gutter
4
Timber rafters SE
SE or TRADA span tables — birdsmouth max 1/3 depth
5
Cross ventilation zone — min clearance per ADoc C
Proprietary cross flow ventilator — Minimum clear air gap per ADoc C
6
PIR insulation at ceiling level
U-value to SE/SAP specification — between and over ceiling joists
7
Vapour control layer
Below insulation — taped at all laps
8
Plasterboard ceiling
Taped and jointed — painted finish
9
Wall plate + holding down strap SE
DPC below wall plate — fixings to SE spec
10
Ventilated soffit
10,000mm² per m run minimum
⚠ Structural requirements — 2 items require SE input
⚠Wall plate holding down strap — fixings to SE specification
⚠Cavity barrier fire resistance — SE or fire engineer to confirm spec
Desktop study available from £200
Key parameters
Exposure zone
Insulation spec
Cavity width
Tips
🟢 Pro tip: Rigid eaves vent tray every rafter bay — clips before insulation. Guarantees required air path regardless of insulation thickness.
🟡 Watch out: Birdsmouth max 1/3 rafter depth. Over-cutting creates stress concentration that splits under snow load.
🔵 Why it matters: Blocked ventilation gap = condensation on timber = rot. You will not see the damage for 5-10 years.
🛒 Recommended products — tiered by specification
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Tier 1Marley Cloaked Verge System natural slateToolstation
Premium+Cromar Pro-Slate High Resistance Underlay 50mTravis Perkins
ROOF-RIDGE-01
Tier 0 — Preview
Apex / Ridge detail
Traditional slate roof — mitred ridge tile — mortar bedded — BS 5534 compliant
⚠ 2 structural requirements on this detail
ROOF-RIDGE-01
Apex / Ridge detail
Traditional cut roofNatural slateRidge2 SE requirements
⚠ Example detail only — confirm all specifications with a structural engineer before construction. Do not scale from this drawing.
Build-up layers
1
Ridge tile bedded and jointed in mortar
Mechanical fix also required per BS 5534:2014
2
Wide overlay band — high resistance underlay
Overlaps main underlay both sides at ridge apex
3
Breathable high resistance underlay
Continuous from eaves to ridge — no gaps
4
Natural slate — top and shoulder courses
Maintain gauge — fix per manufacturer instruction
5
Timber ridge beam SE
SE to specify section size and connections
6
Timber rafters SE
SE or TRADA span tables — opposing pairs at ridge
7
PIR insulation at ceiling level
U-value to SE/SAP specification target — over and between ceiling joists
8
Vent position and number
Dependent on roof area, airtightness, insulation type
⚠ Structural requirements — 2 items require SE input
⚠Ridge beam sizing — SE specification required
⚠Rafter sizing and spacing — SE or TRADA tables required
Desktop study available from £200
Key parameters
Exposure zone
Insulation spec
Cavity width
Tips
🟢 Pro tip: BS 5534:2014 requires mechanical fixing of ridge tiles. Mortar alone is no longer compliant. Specify dry ridge or clips as standard.
🟡 Watch out: Ridge board is non-structural. Remove ceiling joists without an engineered tie and the roof will spread outward.
🔵 Why it matters: Mortar ridge failure is the most common UK roofing maintenance issue. Wind uplift begins years before visible cracking.
🛒 Recommended products — tiered by specification
EssentialRedland Dry Ridge System Universal 6m kitScrewfix
Tier 1Marley Dry Ridge Roll Ventilated 5mToolstation
Premium+Sandtoft Dry Ridge Complete Kit FarmhouseTravis Perkins
FLOOR-INT-02
Tier 1 — 10 details
Timber intermediate floor
Masonry cavity wall — timber joists on hangers — Part E acoustic compliance
⚠ 3 structural requirements on this detail
FLOOR-INT-02
Timber intermediate floor
ResidentialPart EAcoustic3 SE requirements
⚠ Example detail only — confirm all specifications with a structural engineer before construction. Do not scale from this drawing.
Build-up layers
1
T&G floor boarding
Moisture resistant grade — structural ply or equivalent
2
Mineral wool between joists
Acoustic performance — Part E compliance
3
Timber floor joists SE
SE or TRADA span tables — size per span and loading
4
Joist hanger + resin fixed bearer plate SE
SE to specify fixing — resin anchors to masonry leaf
5
Plasterboard ceiling
Taped and jointed — Part E robust detail
6
PIR insulation dot and dab
To internal face of external wall — thermal performance to SE/SAP spec
7
Stainless steel cavity wall tie
Type and spacing per PD 6697
⚠ Structural requirements — 3 items require SE input
⚠Joist sizing and span — SE or TRADA span tables required
⚠Joist hanger specification — SE to confirm connection type
⚠Resin anchor specification for timber bearer plate — SE design
Desktop study available from £200
Key parameters
Exposure zone
Insulation spec
Cavity width
Tips
🟢 Pro tip: Joist hangers at every bearing — never rely on built-in ends. Shrinkage causes squeaks and settlement.
🟡 Watch out: Part E — harder floor finishes need resilient strips between joists and boarding to maintain compliance.
🔵 Why it matters: Acoustic flanking paths destroy Part E. Ensure service void battens are isolated from structure.
🛒 Recommended products — tiered by specification
EssentialJoist Hanger Single Galvanised (pack of 10)Screwfix
Tier 1Rockwool Flexi Slab (pack — size per SE spec)Toolstation
Premium+Novia Gold Acoustic Membrane 50m rollTravis Perkins
ROOF-FLAT-01
Tier 1 — 10 details
Flat roof — masonry abutment
Single ply membrane — timber firings — galvanised flashing chased into brickwork
⚠ 3 structural requirements on this detail
ROOF-FLAT-01
Flat roof — masonry abutment
Flat roofSingle plyMasonry abutment3 SE requirements
⚠ Example detail only — confirm all specifications with a structural engineer before construction. Do not scale from this drawing.
Build-up layers
1
Single ply roof membrane
Draped over and down upstand — minimum height per manufacturer specification
2
Insulated upstand
Continuity of insulation at wall junction — U-value to SE/SAP specification
3
Galvanised flashing
Chased into brickwork — mortar re-pointed — weatherproof sealant
4
Timber roof joists SE
SE to specify size and spacing per span and loading
5
Timber board fixed to firings
Provides deck for membrane — structural grade OSB or ply — thickness to SE spec
6
Timber firings — laid to falls SE
Minimum fall to outlet — SE to confirm drainage adequacy
7
Rigid PIR insulation
U-value to SE/SAP specification — warm deck above joists
8
Joist hangers + resin anchors to masonry SE
SE connection design — stainless in external locations
⚠ Structural requirements — 3 items require SE input
⚠Timber joist sizing — SE specification required
⚠Joist hanger and resin anchor — SE connection design required
⚠Timber firings layout for drainage falls — SE to confirm structural adequacy
Desktop study available from £200
Key parameters
Exposure zone
Insulation spec
Cavity width
Tips
🟢 Pro tip: Minimum falls required — tapered insulation preferred over site-cut firings. Supplier provides free layout drawings from your plan and outlet positions.
🟡 Watch out: Upstand minimum height from finished surface — not deck level. Measure before membrane is dressed.
🔵 Why it matters: Ponding water accelerates membrane degradation. Any standing water 48hrs after rain is a defect.
🛒 Recommended products — tiered by specification
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Tier 1Kingspan Kooltherm Floorboard (depth per SAP calc)Toolstation
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CONC-FDNTS-01
Tier 1 — 10 details
Perimeter foundation detail
Full fill cavity wall — trench strip foundation — insulation below slab
⚠ 4 structural requirements on this detail
CONC-FDNTS-01
Perimeter foundation detail
New buildExtensionGround floor4 SE requirements
⚠ Example detail only — confirm all specifications with a structural engineer before construction. Do not scale from this drawing.
Build-up layers
1
Facing brickwork
Class B engineering bricks below DPC
2
Full fill mineral wool cavity insulation
BBA certified — sheltered/moderate exposure only
3
Load bearing blockwork inner leaf SE
SE to specify block strength class
4
Stainless steel cavity wall tie
Type and spacing per PD 6697
5
Trench fill strip foundation SE
Concrete mix to SE specification — SE to specify width and depth
6
Reinforced concrete ground bearing slab SE
SE to specify thickness and mesh
7
Rigid PIR insulation below slab
To achieve U-value to SE/SAP specification target
8
DPM on sand blinding
Heavy duty polythene DPM — lapped and sealed at all joints
9
Perimeter insulation upstand SE
Prevents thermal bridging at slab edge — SE to confirm
⚠ Structural requirements — 4 items require SE input
⚠Foundation depth — SE to specify per ground conditions
⚠Reinforcement specification — SE design required
⚠Trench fill concrete mix — SE to specify
⚠Slab reinforcement — SE to confirm mesh or RC
Desktop study available from £200
Key parameters
Exposure zone
Insulation spec
Cavity width
Tips
🟢 Pro tip: Agree top of concrete level with your engineer before the pour — brickwork courses to DPC must be coordinated.
🟡 Watch out: Trees on clay sites — foundation depth may need to increase significantly. Check NHBC 4.2 before setting out.
🔵 Why it matters: Made ground at formation — stop and call the SE. Never concrete over unknown fill material.
🛒 Recommended products — tiered by specification
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Tier 1Rockwool Full Fill Cavity Slab (depth per SE spec)Toolstation
Premium+Kingspan Kooltherm K103 Floorboard (depth per SAP calc)Travis Perkins
ROOF-FLAT-02
Tier 2 — 25 details
Flat roof rooflight detail
Single ply membrane — insulated upstand — doubled timber joists at opening
⚠ 2 structural requirements on this detail
ROOF-FLAT-02
Flat roof rooflight detail
RooflightFlat roofOpening2 SE requirements
⚠ Example detail only — confirm all specifications with a structural engineer before construction. Do not scale from this drawing.
Build-up layers
1
Single ply roof membrane
Draped over upstand — minimum height above finished roof level per manufacturer specification
2
Upstand — insulated internally
Continuity of insulation — internal finishes to upstand
3
Timber roof joists — doubled at opening SE
SE to specify where joists are cut and trimmed around opening
4
Timber board on firings to falls
Falls directed away from rooflight to perimeter outlet
5
Rigid PIR insulation
To achieve required U-value — warm deck above joist level — per SAP calc
6
Minimum height upstand
Measured from finished roof surface — not deck level
⚠ Structural requirements — 2 items require SE input
⚠Doubled or tripled timber joists around opening — SE to specify
⚠Upstand kerb structural specification — SE design for larger rooflights
Desktop study available from £200
Key parameters
Exposure zone
Insulation spec
Cavity width
Tips
🟢 Pro tip: Double or triple joists at all four sides of the opening — not just the two trimmer sides. Full perimeter enhancement required — SE to specify.
🟡 Watch out: Upstand height is measured from the finished roof surface — not the deck. Allow for insulation and any paving build-up.
🔵 Why it matters: Rooflight upstands below 150mm are the most common source of flat roof water ingress. Most frequently missed on NHBC inspection.
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