Selecting  Installers.

Some questions to ask.

External Wall Insulation (EWI)

Preparation and Property Impact
External Wall Insulation can significantly change the look and function of your property, so it’s important to understand the process in detail before work begins. Confirm what insulation system will be used, its thickness, and the finish type (e.g. render, brick-slip, or cladding). Ask how the installers will deal with fixtures and features such as satellite dishes, alarm boxes, lights, air vents, overflow pipes, and external taps—these should all be properly removed, extended, and reinstated, not simply covered over.

Openings and Details
Discuss how the system will accommodate windows, doors, and sills, as these may need to be extended or replaced to ensure proper sealing and to prevent water ingress. Check that drip beads, stop beads, and corner trims will be installed neatly and to specification for a high-quality, durable finish.

Ventilation and Airflow
Make sure that ventilation and airbricks are not blocked or removed. Ask how they will be extended through the insulation system to maintain airflow and prevent damp or condensation. Obtain a clear ventilation specification, and ensure the finish matches or complements your property’s appearance.
For homes with fireplaces or open flues, ask about spillage testing and combustion ventilation to ensure safety and compliance.

Groundworks and Damp-Proof Course
Confirm that the insulation will finish above the damp-proof course (DPC) and that appropriate base trims and drainage channels will be installed. The system should not bridge the DPC unless designed to do so, as this can lead to moisture problems. Ensure that any existing damp or drainage issues—including blocked gutters or damaged downpipes—are addressed before insulation begins.

Aesthetics and Boundaries
If your home is part of a terrace, semi-detached, or adjoins another property, ask how the system will terminate at party walls, fences, or neighbouring structures. Ensure that detailing will be neat and watertight. For listed buildings or properties in conservation areas, confirm that planning permission or building consent is in place.

Safety and Compliance
For homes with chimneys, fireplaces, or combustion appliances, ask about spillage tests and combustion ventilation to ensure safety after the installation.

Documentation and Clean-Up
Request written details of all materials, fixings, and finishes, including manufacturer names and warranty information. Confirm that all waste and debris will be removed and agree on a timeline for completion and clean-up.

Finally, ensure you have full contact information for everyone involved in the project, including the installation team, project or site manager, and—if installed through a UK grant scheme, the Retrofit Coordinator responsible for oversight and compliance.

Internal Wall Insulation (IWI) and Room-in-Roof Considerations.

Disruption and Reinstatement
Internal Wall Insulation can be highly disruptive, often requiring the removal of features such as skirting boards, window sills, coving, door frames, electrical sockets, light fittings, and radiators. Confirm that your installer will reinstate all removed items and specify whether they will be restored or replaced. Ensure that qualified tradespeople—such as joiners for woodwork and plumbers for wet work—will carry out these tasks, and get this commitment in writing.

System and Detailing
Ask which insulation system will be used and how the installer plans to treat complex areas such as coving, cupboards, or meter locations. For room-in-roof spaces, confirm that any loft or eaves hatches will be properly insulated and professionally fitted, not simply boarded over. If you use roof storage, ensure this area remains accessible and structurally suitable for use once insulated.

Check that all electrical, alarm, TV, satellite, and internet cables will be correctly routed through the insulation and fully reinstated afterwards.

Ventilation and Safety
A ventilation system should be installed as part of the works. Obtain a detailed specification to confirm it meets high standards of performance and finish. For homes with fireplaces or open flues, ask about spillage testing and combustion ventilation to ensure safety and compliance.

Pre-Installation Checks and Documentation
Before work begins, inspect the external walls, damp-proof course, gutters, and downpipes. Any existing issues must be identified and either rectified by the installer or formally agreed with you in writing, as they can compromise insulation performance and cause long-term problems.

Finally, confirm that all debris will be cleared and agree on a timeline for completion and cleanup. Request full contact details for everyone involved, including the office manager, installation team (noting if subcontractors are used), and—if the work is part of a UK grant scheme—the Retrofit Coordinator overseeing the project.

Cavity Wall Insulation (CW) considerations.

Scope and Drilling
Confirm that all suitable wall areas will be insulated, which may involve internal drilling. Discuss in advance where drilling will occur and what materials will be used to fill and finish the holes afterwards to ensure a neat appearance.

Garages and External Finishes
For attached but unheated garages, talk through insulation options—particularly if shelving, cupboards, or other fixtures will need to be removed or adjusted. When drilling into external walls, ask what colour of mortar will be used to fill the holes, especially on rendered or painted surfaces. Confirm whether installers will repaint or touch up the finish to match the existing façade.

Material and Clean-Up
Find out exactly which insulation material is being used and take the time to research its properties and suitability for your home. Clarify whether the installation team will be responsible for cleaning up spills, dust, or debris, and have this commitment documented in writing. If you have outdoor features such as ponds or livestock areas, inform the installers so they can take precautions against overspill.

Ventilation and Safety
If new ventilation is required, request a clear specification and ensure all installations are completed to a high standard of finish. For homes with fireplaces or open flues, ask about spillage tests and combustion ventilation to maintain safety and compliance.

Pre-Installation Checks and Aftercare
Inspect external walls, damp-proof courses, gutters, and downpipes before work begins. Any existing damp or drainage issues must be resolved first, as they can undermine the effectiveness of the insulation and lead to long-term problems. Finally, confirm that all debris will be removed and agree on a clear timeline for completion and cleanup—especially important for removal and refill projects.

Underfloor Insulation (UFI) considerations.

Materials and Installation
It can be challenging to assess conditions beneath the floor unless you have a basement. Confirm the type, thickness, and support method of insulation being installed, and ensure all accessible areas will be covered. If floorboards need to be lifted, be aware this can cause damage—ask whether replacements will match the original boards to maintain appearance and consistency. Take pre-installation photographs for reference.

Cross Ventilation
Adequate underfloor ventilation is essential. Make sure any existing vents or decorative grilles are retained or replaced with alternatives that are both functional and visually appropriate. Request written confirmation of how cross-flow ventilation will be maintained or improved, including details of the units being installed. The system should allow sufficient airflow to prevent moisture buildup and stop water ingress.

Basement Insulation
If a basement is being insulated, ask about fire safety compliance and verify that all work adheres to current building regulations. It’s worth doing your own research for added assurance.

Ventilation and Safety
If a ventilation system is included, obtain a detailed specification and confirm it will be installed to a high standard. For properties with fireplaces, request information on spillage tests and combustion ventilation to ensure safety and compliance.

Pre-Installation Checks and Cleanup
Inspect external walls, damp-proof courses, subfloor ventilation, and rainwater systems (gutters, downpipes, etc.) before work begins. Any existing damp or drainage issues must be resolved first, as they could compromise the insulation and cause long-term damage. Finally, confirm that all debris and waste materials will be removed and agree on a clear timeline for completion and cleanup.

Loft Insulation (LI) considerations.

Materials and Impact
Ask which insulation materials will be used—such as spray foam, mineral wool, or PIR boards—and make sure you understand their limitations and how they may affect your property’s insurance or mortgage eligibility.

Access and Storage
Discuss how the installation will impact access to essential services in the loft, such as boilers or solar inverters, and whether storage areas will still be usable or need adjustment.

Electrical Safety
If you have recessed down lights, these must be properly protected to prevent air leakage and potential overheating. Suitable covers or fire-rated caps should be used. For electric showers or other circuits with cables running through the loft, ensure proof is provided that the cables are not buried within insulation, as this can cause overheating.

Pipework and Loft Hatch
All exposed water pipes should be fully insulated. The loft hatch should also be insulated and drought-proofed to a professional standard—avoid makeshift solutions like loosely stapled insulation.

Ventilation and Timber Protection
Adequate airflow in the loft is essential to prevent condensation and protect the roof timbers. Confirm that ventilation will be maintained or improved as part of the work.

Whole-Home Ventilation and Safety
If a new ventilation system is being installed, request a clear specification to ensure it meets high-quality standards and finishes. For homes with open fireplaces, ask about spillage tests and combustion ventilation to ensure safety and compliance.

Gas Boiler considerations.

Gas Supply
Most combination boilers need a larger gas supply pipe than older systems, often requiring an upgrade from the meter. Before installation, confirm the planned gas pipe route to avoid unnecessary external runs if an internal route is possible. If the pipe must run outside, ensure it’s properly clipped and installed in line with regulations.

Heating Controls
Discuss your heating controls and where the thermostat will be located. It should be positioned in a room without a thermostatic radiator valve (TRV) or any secondary heat source such as a fire or cooker, to ensure accurate temperature readings.

Condensate Drainage
All condensing boilers produce condensate that must be drained safely. Ideally, this drainage point should be located indoors. If the condensate pipe must run externally, it needs to be insulated with Class 0 lagging. Confirm the type of insulation being used and how it will be secured and supported.

System Clean and Preparation
Ensure all debris will be removed during installation and clarify when this will happen. Most boiler manufacturers require a full system flush before fitting the new unit—this is essential. Make sure the installer carries it out, and ideally, observe the process. The correct use of cleaning and inhibitor chemicals is vital for system health, and their use should be recorded in the Benchmark log (the boiler’s installation and service record). Ask for a copy for your files.

Warranty and Guarantees
Confirm both the manufacturer’s warranty and the installer’s guarantee, particularly regarding leaks and workmanship. Once the boiler is installed, it’s a good idea to call the manufacturer directly after a few weeks to confirm that your warranty is fully registered and active.

Solar PV (SPV) Considerations.

Panel Direction
You may already know the direction your property faces, but installers might suggest positioning the panels differently. This could be due to access issues, roof condition, or other practical constraints. However, the optimum orientation delivers the best performance, so make sure your installer prioritises efficiency over convenience.

Inverter Location
The inverter should be installed somewhere easy to access for inspection, servicing, and maintenance, while also being protected from the elements. Some models are suitable for outdoor installation, provided they’re shielded from direct sunlight and rain. If you live near the coast, ask about corrosion resistance and whether additional protection is needed.

Monitoring Meter
The generation meter should be positioned where it can be easily read and checked regularly. Make sure it’s visible enough to monitor energy production and detect early signs of faults (for example, if it isn’t blinking in daylight).

Paperwork and Certification
Confirm the expected timescales for all necessary documentation, including MCS certification, DNO approval, and any paperwork your energy supplier may require.

Warranties and Guarantees
Clarify the warranty terms and guarantee lengths for all equipment. Make sure you know who to contact in case of faults or system failure.

Get Everything in Writing: Once you’ve decided an installation company, make sure to get all agreements, including costs, timelines, and scope of work, in writing. This helps protect both parties and ensures clarity and accountability throughout the project.

Air source Heat Pumps. (ASHP)

System Type and Design

Ask your installer to explain which make, model  of heat pump is being fitted and why it’s suitable for your property. Confirm that the system has been properly sized for your home, an undersized or oversized unit can reduce efficiency and increase running costs. Request a full design calculation (MCS or equivalent) showing heat loss per room, flow temperatures, and emitter sizing. Ask what refrigirant is used within the pump (R32, R290 etc). Ask about hybrid systems to help in the winter months.

Outdoor Unit Location
The external unit should be positioned where airflow is unrestricted but noise and vibration will not affect you or neighbours. It must sit on a stable, level base (often a concrete pad or anti-vibration plinth) and be clear of obstructions such as fences or foliage. If located near boundaries, confirm it meets local noise regulations and planning guidance. For coastal or exposed locations, ask about corrosion-resistant finishes and protective coatings.

Internal Components
Confirm where the indoor cylinder, buffer tank, and controls will be located. These should be easily accessible for servicing and maintenance, with pipework neatly installed and insulated. Discuss how existing systems—such as radiators or underfloor heating will be adapted or replaced, and ensure the flow and return pipe sizes are appropriate for the new system.

Condensate and Drainage
Heat pumps produce condensate water, particularly in colder weather. This must be drained safely away from the base unit, ideally into a proper soakaway or drain. The pipework must not freeze, so confirm that suitable insulation and gradients are in place.

Electrical and Controls
Ensure the electrical supply is adequate and compliant with regulations, with a dedicated isolator switch. Ask about the control system whether it will use smart thermostats, weather compensation, or load compensation and how to use these features for maximum efficiency.

Ventilation and Safety
Proper air circulation around the external unit is essential for performance. Check that there’s enough clearance on all sides, as specified by the manufacturer. For homes with fireplaces or combustion appliances, ensure that spillage tests and combustion ventilation are carried out if any flues or ventilation systems are affected during installation.

Groundworks and Protection
If installing a ground source heat pump, confirm the ground loop layout (horizontal trenches or boreholes), and request documentation of where pipes are buried for future reference. For air source units, confirm that rainwater runoff from roofs won’t drip onto the unit and that the area around the base remains well-drained and clear of standing water.

Warranties, Maintenance, and Support
Ask for details of warranties and service agreements for both the equipment and installation. Heat pumps require annual servicing to maintain performance and warranty validity, so ensure you receive a maintenance schedule and the installer’s or manufacturer’s contact details.

Paperwork and Certification
Ensure you receive all necessary documentation, including MCS certificates, DNO notifications, and user manuals. These are essential for warranty registration, grant schemes (such as the Boiler Upgrade Scheme), and resale value.

Cleanup and Completion
Confirm that all debris and packaging will be removed and agree on a clear completion timeline. Obtain written contact details for the installation company, lead installer, and if installed through a UK grant scheme the Retrofit Coordinator responsible for the project.