RIGHT BUILD GROUP · RICHMOND
House Extension in Richmond
Follow rainwater beyond the roof edge. Coordinate falls, outlets, overflow and the checked drainage route before the extension’s appearance becomes fixed.
- Rainwater route considered end to end
- Roof and ground drainage coordinated
- Maintenance access planned early
ARCHITECTURAL HOUSE EXTENSIONS
A hidden gutter still needs somewhere suitable to drain.
A shallow roof edge or concealed outlet can be an attractive detail, but its water route must work beyond the visible facade. Identify how the roof is drained, where the pipe runs and what receives the water. Do not begin with a soakaway or existing connection assumed suitable simply because there is space for it on the sketch.
The roof and its connected construction form part of the scope to agree for Right Build’s house extension work. For a Richmond home, bring the relevant designer and drainage advice into the roof discussion before the footprint and external finishes are fixed. The room, roof and ground route should form one coordinated proposal.
FOOTPRINT STUDIES
Compare roofs with their complete drainage route.
Each footprint changes where water is collected and how it reaches the ground arrangement.
REAR EXTENSION
A rear roof with a planned outlet
A rear addition may create a roof edge close to garden doors or a boundary. Show falls and outlet positions with the elevation. A downpipe should not appear as an unplanned obstruction after the glazed facade has been ordered.
Review the external level and the remaining garden use around the route. Keep maintenance and inspection practical. A pipe concealed within a narrow gap is not a successful detail if routine access later depends on dismantling the enclosure.
SIDE-RETURN EXTENSION
A side return beside the old wall
Side infill can create a constrained roof junction where the old house, boundary and new construction meet. Assess where water goes and how that junction is weathered. The narrowness of the space should prompt coordination rather than an assumption that a concealed channel will solve it.
Record existing drainage and any inspection points in the passage before it disappears. If the proposal changes access or a connection, resolve the replacement arrangement with the relevant advisers before the floor and furniture conceal the route.
WRAPAROUND EXTENSION
One side-and-rear water strategy
A wraparound brings several roof planes and the old projection together. Draw the falls, collection and downstream route across the whole footprint. Separate side and rear details can miss a corner where water has no sensible path or maintenance is awkward.
Assess the combined planning proposal, including the side component. A resolved drainage arrangement does not establish permission, just as planning approval does not provide the technical roof and outfall detail. Keep those decisions coordinated but distinct.
OLD ROOM / NEW ROOM
Trace the route on one accepted drawing.
Start at the roof surface and follow collection, outlet, pipe and discharge. Identify who designs each part and who coordinates the interfaces. A roof supplier’s outlet detail and a ground-drainage plan need to meet physically, not simply appear in separate documents.
Where infiltration is proposed, obtain the relevant assessment of suitability rather than assuming every garden accepts a soakaway. Where a connection is proposed, establish its nature and the relevant permissions or agreement. The appropriate solution follows the site and regulatory requirements, not a standard label added to the plan.
Coordinate the kitchen layout and the external facade with the route. Keep inspection and service access available after fitting. Define repairs to the old rooms within the refurbishment scope so the visible connection is completed deliberately.
Ask how the chosen roof system manages blockage or an exceptional event through the appropriate design, including overflow provision where required. Avoid a detail whose failure would be hidden until water enters the room. The household does not need to calculate the system; it needs the relevant designers to explain the accepted route and the maintenance tasks that keep it usable.
Check the positions at the end of the route against how the garden will be used. A pipe, inspection point or outlet that works on an empty site may become obstructed by a fixed planter or terrace detail. Keep the relevant components on the landscape and fit-out information. The household can then choose furniture and planting without unknowingly blocking access that the accepted system needs.
GROUND, LOADS & CONNECTIONS
Foundations and roof support need the drainage information.
Ground and the outfall arrangement
Foundation design depends on loads, ground, trees, drains and surrounding construction. The proposed rainwater route is one input, not a reason to choose a standard trench depth. Establish relevant investigation and interpretation responsibilities before groundwork is treated as fixed.
Consider the relationship between excavation, existing foundations and the proposed drainage. Do not undermine retained or adjoining structures. If the outfall strategy changes after assessment, review its consequences for the footprint and support rather than treat it as a hidden service substitution.
If more than one storey is intended, assess both levels and their complete load path before commitments. A single-storey roof and its drainage do not establish that a future upper extension is feasible. Define the building being designed now.
Roof geometry and the old-house opening
Structure, falls and roof build-up affect ceiling depth and the visible edge. Coordinate those layers before choosing a shallow profile. The engineer and relevant roof designer need the actual proposal, including openings and the relationship with the old wall.
The connection into the house may need beams, bearings or columns and an appropriate temporary-support method. Plan the opening stage, security and weather protection. A roof that appears complete from outside should reach its relevant readiness before the old enclosure changes.
THE DESIGN TRADE-OFFS
Compare the room and roof as a complete system.
Keep the discharge and maintenance questions visible within each option.
| Extension | Useful gain | Main check | Resolve before ordering |
|---|---|---|---|
| Rear | A larger garden-facing room | Outlet positions beside the facade | Roof-to-ground route |
| Side return | Width beside the old projection | Constrained junction and lost inspection access | Collection and accessible connections |
| Wraparound | Connected side and rear space | Combined falls at the corner | One roof drainage design |
| Two storeys | Rooms on both levels | Full support and roof arrangement | Both levels and services coordinated |
ROOF, GLASS & DAILY COMFORT
Let glazing fit the roof's working geometry.
Rooflights can help the deeper part of the room, but their placement needs coordination with falls, structure and the old room’s section. A long glazed strip should not force an unresolved drainage corner. Compare useful light with the appropriate roof-system detail.
Consider orientation, shading, privacy and opening ventilation for the occupied space. More glass does not guarantee comfort or daylight in the retained room. Review the combined depth and furniture positions rather than judge only the new garden elevation.
Keep access for rooflight care, gutters and outlets practical. The finished garden, planting and furniture should not block the method intended for inspection. Ask the relevant suppliers what routine maintenance the selected products need and retain that information with the house records.
THE COMPLETE BUILDING
Resolve water above and below ground.
Drain ownership and agreed intervention
Locate actual drains and chambers and establish whether routes are private, public sewer or relevant lateral drain. Maps can be incomplete. The rainwater proposal and existing foul drainage should be understood rather than connected together casually because a pipe is nearby.
Where undertaker agreement for build-over or another intervention is required, coordinate it before construction. Planning approval does not replace that process. Do not assume a diversion, connection or chamber relocation will be accepted merely because it suits the furniture plan.
Weathering and continuous enclosure
Trace a rainwater pipe through the proposed enclosure section, not just across the elevation. Its penetration and supports must fit the chosen wall or roof system while preserving the designed insulation and moisture protection. Resolve that weathering detail before lining the interior, so a later pipe alteration does not disturb finished surfaces unnecessarily.
Confirm the applicable energy and ventilation approach and keep services reachable. Purpose-made covers or interior closures can be included in the carpentry scope after their access and technical functions are defined. Avoid boxing that makes the accepted route impossible to inspect.
RICHMOND / THE EXISTING SETTING
Survey Richmond levels without assuming the drainage answer.
The Richmond Hill character analysis records views and groups of mainly two-storey stock-brick buildings with slate roofs in Richmond Hill. Use a measured rear elevation to develop the new roof’s relationship with the house, then survey its water route separately. The character description gives architectural context; drainage design needs the actual levels, ground and connections.
Record the actual house and garden levels, existing outlets and any known drainage history. Bring available plans as background and identify what requires checking. A slope visible outside is not a complete outfall design or permission to send water towards another property.
Mark the proposed outlets, downpipes and any external intervention on the information used for relevant planning or heritage advice. Establish who controls land and services along the intended route. This keeps a concealed drainage choice from becoming an unreviewed change after the roof and garden facade have already been accepted.
FROM FIRST BRIEF TO FINAL DETAIL
Follow the water through the design.
Survey and brief
Record the room, roof context and existing drainage.
Assess the route
Resolve collection and discharge with relevant advice.
Coordinate approvals and detail
Align structure, envelope and required authorisations.
Construct the system
Build to the accepted roof and ground information.
Review and maintain
Keep operation and routine-care information available.
SCOPE, ALLOWANCES & SEQUENCE
Compare the roof and discharge together.
Ask quotations to include the same roof falls, outlets, pipes and accepted ground route. A roof covering price alone does not show the cost of the complete system. Include access and making good where agreed.
Separate selected products from unresolved outfall or ground questions. Agree the investigation and how findings are authorised. Keep an appropriate allowance for genuine uncertainty instead of assuming a simple soakaway in order to reach a lower starting figure.
If the route changes, compare its consequences for structure, facade and external reinstatement. Keep the accepted drawings and maintenance detail with the scope. A concealed product saving should be judged alongside the work and access it creates elsewhere.
Ask for the quotation to distinguish a selected roof product from the complete drainage arrangement. Confirm who provides the connecting detail and any required ground investigation. If several suppliers are involved, allocate the interface explicitly rather than assume the final installer takes responsibility for every upstream and downstream component. This makes a later design change easier to price and review while the physical route can still be altered.
| Cost factor | Question for the quotation |
|---|---|
| Roof collection | Are falls, outlets and required overflow details included? |
| Ground route | What evidence supports the proposed discharge? |
| Authorisations | Which agreements apply to affected drains or land? |
| Maintenance | How is inspection access preserved after finishing? |
ARCHITECTURAL CONCEPTS
Architectural studies of roof and ground relationships.
Illustrative concepts explore extension form, not completed Richmond projects or drainage designs.
QUESTIONS BEFORE COMMITTING
Plan with the right questions.
Can a soakaway be assumed for every garden?
No. Obtain the relevant suitability assessment and design for the actual site before relying on infiltration.
Should downpipes be considered before glazing orders?
Yes. Their position and maintenance can affect the facade and routes around it.
Does planning approval authorise a sewer intervention?
No. Establish any relevant undertaker process and agreement separately.
Can rainwater use any nearby drain?
Identify the route, ownership and appropriate connection requirements before design or construction relies on it.
Why discuss overflow before the roof is built?
The relevant system design should consider how water is managed when required, rather than leave an unplanned hidden failure route.
Do rooflights affect drainage design?
Their position, structure and weathering need coordination with the roof falls and outlets.
What maintenance information should we keep?
Retain the accepted route, access details and product-care instructions for relevant roof and drainage components.
What makes rainwater-related quotations comparable?
Use the same complete collection, discharge, access and reinstatement scope, with unresolved questions identified.
HOUSE EXTENSIONS NEARBY
A different address, a fresh assessment.
LET’S DISCUSS YOUR EXTENSION
Plan the whole rainwater route before the roof edge.
Discuss the room, roof and checked discharge arrangement as one extension proposal.