Replace a window with patio doors: costs and planning
Planning for your terrace and garden
Turning a window into a direct route to a terrace, balcony or garden may look like a simple swap on a plan. On site, it usually affects the opening, lower wall, floor build-up, waterproofing and façade junction. Choose the door for the complete junction, not its appearance alone. Consider usable clear width, the threshold you want, opening direction, room for hinged leaves or sliding panels, and finished internal and external floor levels. Resolving these points before measurement and quotation makes door systems easier to compare and helps avoid an attractive opening that later needs an awkward step, blocks circulation or requires extensive extra work.
Treat the conversion as an opening project
The key difference between replacing a window and creating a door lies below the existing sill. The lower wall is removed, the opening extends to the intended floor level and the transition outdoors must be made durable. The existing lintel above may shape the project, but its suitability and the consequences of widening need professional assessment. Shutter boxes, radiators, sockets, window boards, internal and external render, and any insulation may also be affected. A reliable quotation therefore covers more than the new unit: it should describe removal, protection, reveal work and reinstatement of adjoining surfaces. Never compare a single “patio door” line with another total price where removal or junction work is defined differently.
Begin with a record of the existing situation, including photographs inside and out. Note the current window width and height, sill height, wall thickness, visible obstacles, internal floor and terrace-finish levels, and the distance from the material access point. State where the door will lead: level terrace, step, balcony or narrow passage. These details do not replace a survey, but they make discussions specific. At the appointment, ask whether the desired clear opening remains achievable after the frame and threshold are fitted. A structural opening is not the same as passage width. Also clarify which surfaces are opened and reinstated, and who coordinates structural work, window fitting, waterproofing, flooring and façade repairs.
Choose the door type around daily use
The right solution follows your everyday route. For frequent access to the garden, a single-leaf door may be enough where the clear width works and the leaf has sensible room indoors. A single-leaf inward-opening patio door can suit a room that can accommodate its swing. Check the furniture layout: a dining table, curtain or radiator should not obstruct the handle or open leaf. The outdoor area stays clear, but a defined movement zone is needed inside. If you go outside only occasionally, do not automatically choose a larger unit; weigh the extra glazing against operation and the scale of the conversion.
If the opening is mainly intended to increase light and views, with occasional access, wider arrangements can be attractive. Patio Life lift-and-slide doors offer an alternative where the moving panel slides sideways instead of swinging into the room. This can work well in front of furniture or a dining area by the façade. It still calls for a careful decision on fixed and moving sections, handle side and the clear space beside the unit. Double-leaf hinged doors create a generous transition when both leaves are open, but require swing space. Ask more than “Which door do I like?” Consider how you will actually pass through with a tray, pushchair, garden equipment or while ventilating the room.
Plan width, height and sightlines together
A door opening does not feel generous through its external dimensions alone. Frame widths, mullions, leaf divisions and the threshold determine what remains for walking through and looking out. Draw the proposed arrangement to scale on the room plan. Mark opened leaves, routes to the kitchen, seating and the position of curtains or shading. Include planters, railings, steps and terrace furniture in the same external sketch. A broad opening can transform a room, but it can also leave less continuous wall for cupboards, radiators or pictures. In a small wall with a window recess, door position is often more important than maximum width.
Height often receives serious attention only at final measurement. The top of the new unit may follow the existing window height, but its lower edge relates to the finished floor. If the internal floor or external finish will later be renewed, reference levels change. Record separately the structural floor, finished floor, existing external finish and planned external finish. The installer needs these details before setting the threshold and junction. On an asymmetrical wall, a fixed glazed panel beside the passage can add daylight without making the moving section unnecessarily wide. A single fixed glazed side panel is one possible product alternative. Specify exactly which side it sits on and how wide the actual passage remains. Also check that the fixed area can still be reached externally for glass cleaning or inspection of nearby junctions. The extra width should bring a clear benefit for light or views without taking unnecessary wall space. Consider whether a central division frames the garden, path or neighbouring property pleasantly, or interrupts the view.
Set the floor junction and threshold early
The transition from the room to the terrace is among the most consequential decisions in this conversion. A low threshold makes access easier and can visually connect indoors and outdoors. Its planning concerns more than the door unit: it involves build-up heights, water management, waterproofing and the construction immediately outside the door. If external paving slopes towards the façade or is already high, a new finish build-up or terrace-drainage work may be needed. A visible step may fit an existing setting more simply, but changes comfort and furnishing. There is no universally correct detail; it must suit the existing conditions and planned outdoor area.
Ask for a clear explanation of the floor junction in the quotation: where is the finished internal floor level? How does the external finish meet it? Where does surface water drain? Which work belongs to the window installer, and which to waterproofing, terrace or façade trades? “Installation included” does not answer these questions. Especially with a later-raised timber deck or paved surface, do not decide the final height after ordering. A sensible sequence fixes the level concept first, then the element height. Also ask what weather protection is planned during works, so open areas are not exposed unnecessarily.
Decide opening direction from room and terrace
For hinged doors, opening direction affects every day after installation. Inward-opening leaves stay out of the way outdoors but need a clear swing area in the room. Outward-opening versions free the internal floor but project onto the terrace or balcony. There, seating, railings, steps or a narrow route may make use difficult. A single-leaf outward-opening patio door therefore works only where the external area can receive the leaf safely and practically. Show the door fully open, not merely half open, on the plan. Only then do clashes with a table, parapet or route along the house wall become visible.
Wind exposure and the desired operation also deserve discussion with the installer. An outward-swinging leaf should not strike fittings uncontrollably, while an inward-opening leaf should not obstruct circulation in daily use. The handing determines which hand uses the handle and which side you stand on when stepping out. With double doors, establish which leaf will usually be used and when the full opening is needed. Take a sketch of the furnished room to the appointment. This is not a decorative choice: wrongly positioned opening direction remains a daily compromise after completion, even if the dimensions and glazing are otherwise right.
Balance daylight, privacy and façade design
The conversion changes daylight and sightlines in both directions. More glazing can open a room to the garden, but can also increase views in from a path or neighbouring land. Observe the site at different times of day: where does direct sun fall, where might people stand outside, and which furniture needs to remain? Privacy need not mean permanent blackout. The opening position, planting, curtains, internal screening and external shading can each perform different tasks. Plan them early so their fixing, opening clearance and operation do not later conflict with handles or leaves.
Externally, the new division should suit the façade without making internal use worse. Existing window axes, glazing bars and surrounding details can offer guidance. Where a traditional appearance matters on an older façade, a single-leaf heritage-style outward-opening patio door may be a design alternative worth considering. The product name describes style, number of leaves and opening direction, not suitability for your specific building. Dimensions, junctions and daily use remain decisive. Photograph the whole façade rather than only the window. This allows axes, sill lines and relationships with neighbouring doors to be assessed together instead of selecting a solution around one isolated wall opening. In Malta, ask a perit to check the Planning Authority classification and any heritage, façade or ownership requirements for the actual property.
Compare quotations by their scope
Costs for this work consist of several packages: planning and survey, window removal, opening and potentially securing the wall, the door unit, installation, internal and external junctions, reinstatement of render or cladding, floor work, disposal and site protection. Depending on the situation, shading, electrical work or terrace alterations may be added. No general total is meaningful without knowing the size, wall construction and outdoor area. Ask for separate, clearly described items rather than a lump sum with no scope. This shows which parts are fixed, which are based on assumptions and which will be dealt with after site findings.
Compare quotations using your own table. Columns should cover unit dimensions, opening type, handing, glazing arrangement, colour or finish, handle side, threshold concept, removal, wall work, waterproofing, external finish, internal plaster and final cleaning. Mark each item “included”, “not included” or “subject to clarification”. A double-leaf outward-opening patio door should be compared not just with a single-leaf door, but with the space needed in front of the façade and the intended use. Check the sequence too: must the terrace be adapted first, can the unit be fitted immediately, and who takes final measurements and when? Bloomcabin delivery is 4–6 weeks, subject to order confirmation; this does not replace coordinated site planning.
Clarify structure, existing fabric and interfaces
Extending a window opening affects the wall. Whether and how it can be done depends on the particular construction, not a blanket rule. A wider opening, unknown masonry, visible cracks, loads above or earlier alterations all require a qualified assessment of the existing situation. Do not commission work on structural fabric from a photograph or wish-list sketch. The assessing professional should know the intended opening width and height, which areas will be removed, and which components connect above or beside it. Only then can the method, any temporary support and the work sequence be defined sensibly.
The interface with the interior is also often underestimated. If a radiator sits below the window, its future location must be coordinated with heating and floor planning. Services within the wall should be identified before opening it. With underfloor heating, screed or sensitive floor finishes, the breakthrough changes more than the façade. Appoint one person or trade to bring dimensions from every sub-plan together. The window installer needs the confirmed structural opening and floor levels; the builder needs the unit data; terrace work needs the junction level. A joint visit before ordering can prevent misunderstandings more cheaply than corrections to an installed unit.
From product enquiry to reliable measurement
Existing dimensions and photographs are enough for an initial enquiry, but ordering requires a binding survey once the opening is resolved. Describe priorities in this order: intended use, approximate passage width, opening type, opening direction, floor transition, design and accessories. This gives the supplier a basis for decisions rather than just a wall width. If you need a large clear passage but have little indoor swing space, sliding doors can be an alternative. For a sliding arrangement, ask specifically about the division between fixed and moving panels and where the passage sits. Only a complete elevation reveals whether the active section is where you really need it.
Before approval, all details should be clear in writing: external and internal elevation, overall size, leaf division, handing or sliding direction, handle position, visible glazing bars if wanted, colour or finish, glazing, threshold and accessories. Ask for unclear terms to be explained. “Left” can be misunderstood without stating the internal or external view; a marked drawing is better. Keep the last confirmed drawing with the quotation. Bloomcabin windows and doors have a 5-year manufacturer guarantee. This does not define what different trade quotations include for the wall, waterproofing or terrace, so record those trades and responsibilities separately.
Prepare the site for a short, clean process
The actual changeover is only part of the appointment. Beforehand, remove furniture from the work area, protect sensitive floors and clear the route from delivery point to the opening. Clarify whether work takes place inside and outside, where materials can be placed, and how dust protection and disposal of the old window will be organised. In poor weather, it is particularly important to know how long the opening can remain exposed and how temporary protection will work. Do not schedule important internal finishing immediately before the conversion if plaster or floor junctions will only be completed afterwards. A clean sequence considers structural work as carefully as the final coat of paint.
After installation, check the agreed appearance and operation with the person carrying out the work: correct opening direction, handle side, division, undamaged visible surfaces and a comprehensible transition to adjoining work. Operate the door yourself and test it in the intended everyday setting, for example with chairs in place or a rug in the room. With a double-leaf inward-opening patio door both leaves and the space needed when open should be checked deliberately. Document outstanding work with photographs and a clear description, such as missing render repair or later adjustment of the external finish. This keeps acceptance of the unit distinct from following trades and makes project completion traceable.
Frequently asked questions
Can patio doors fit any existing window opening?
Not without assessment. Removing the lower wall changes the opening downwards; widening may also affect the sides or area above. Wall construction, the existing lintel, services, floor levels and external area must suit the proposal. Have the specific opening assessed by appropriate professionals and measured definitively before ordering. For Malta, also have a perit confirm the applicable Planning Authority route and site restrictions.
What does it cost to replace a window with patio doors?
A general figure is of little value without inspecting the existing property. Besides the unit, the scope is affected by removal, wall opening, possible support, installation, waterproofing, internal and external junctions, terrace work and access. Request quotations with separate work items. You can then see whether two prices genuinely cover the same work and reinstatement.
Should patio doors open inwards or outwards?
Inward-opening leaves need free space in the room but leave the terrace clear. Outward-opening leaves need space on the terrace or balcony while freeing the interior. Draw the fully opened leaf on both sides. Consider furniture, routes, railings, steps and the preferred handle side before deciding.
When should the terrace be renewed?
Ideally, agree the terrace plan before final measurement. The level and build-up of the external finish affect the door junction and water management immediately in front of it. Raising or replacing the finish later can compromise an already fixed detail. Set the internal floor, external finish and threshold concept together.
What does a supplier need for an initial enquiry?
Useful information includes photographs from inside, outside and of the complete façade, the existing window width and height, wall thickness, internal and external floor levels, intended use, and a sketch of room and terrace. Also state opening direction, design wishes and possible obstacles. The responsible professional takes the binding measurement after the opening has been clarified.
Next step
Converting a window into patio doors is primarily a coordination task. The chosen door unit matters, but is only one component between the wall opening, structure, finished floor levels, waterproofing, external finish and daily use. Start with a clear use scenario and record of the existing conditions. Have the opening professionally assessed, define floor junctions before final measurement, and compare quotations with the same scope boundaries. When drawings, responsibilities and sequence are clear before ordering, the new exit becomes a functional transition rather than a series of later adjustments.
