Restoration, refurbishment and super-insulation of an extensively enlarged 1940s semi, with carbon sequestration and renewables.

A overview to explore all the options and a planning submission.  Bespoke kitchen, rear extension, attic conversion.

Friday, 25^th May 25, 2007

Re;    Hansford Square

Following a full investigation of your home on 3^rd May 2007, we are pleased to describe our findings and main recommendations.

The scope of the full site investigation was to identify and assess the construction techniques and thermal performance of the building and the provision of services, in particular:
 - Water ingress at low level and a recurring leak at the junction with kitchen extension
 - The structural integrity of the bay window above the conservatory
 - The composition of the internal floor and foundation.

The results of the investigation will inform an opinion on:
 - The redevelopment potential of the conservatory area
 - The suitability of the kitchen floor for removal and subsequent redevelopment  with insulation and underfloor heating
 - Any other limitations affecting the suitability of the property for re-use and redevelopment.

Summary

This report describes the findings of the full site investigation on a room by room basis, although there are key issues which re-occurred throughout your home.

Earlier redevelopment of the house appears to have been done poorly in places and without due regard for building regulations. Areas which do not comply include stairs, which present trip hazards, inadequately fire-protected lights, and a lack of ventilation in the shower room. The bay window in the extension requires additional structural support and may indicate the overall care which was taken in previous work.

Increasing the air-tightness of the building will improve its thermal performance, and further benefits can be gained in redeveloping the attic, conservatory and kitchen/garage by taking the opportunity to maximise insulation levels and capitalise on the good solar position of your home.

Location constraints and opportunities

In general the original house is a good example of post-war housing stock, well designed and sturdily built. It is also well sited to take advantage of renewable energy sources, with solar potential excellent  in regard to both planning concerns and practical details. For example, the rear of the house has very good solar orientation, and is not over-shaded.

Initial enquiries to Bath and North East Somerset Council Planning Department indicate that although the house is not sited in a conservation area, it has already been extensively added to and planning permission will be needed if further enlargement is required. However, solar panels, if integral, would not need planning permission. 

Roof and attic

The general impression within the attic room and associated storage areas in the eaves is of poor quality construction and a lack of attention to detail. Investigation in the eaves has shown that insulation levels are minimal at about 3 to 4 inches between the ceiling joists and similar between the roof rafters, which are boarded with plasterboard. The installation of the mineral wool insulation between the rafters has been done in such a way as to prevent ventilation around the timbers. When moisture from the floors below condenses on the cold surface of the roofing felt, the lack of a ventilation gap will allow the moisture to remain in the area, and means that the performance of the insulation will be reduced and there will be a risk of long term damage to the roof structure. 

In general, the quality of insulation fitting is very poor, with a number of gaps and thin spots in the insulation and plasterboard observed. None of the access doors to the eaves are airtight, so the attic room is effectively at ambient external temperature, as the eaves are, unless it is heated. Heat is being lost from the rest of the house due to the lack of separation of the attic from the floor below. Fire protection suitable for a three-storey domestic property has also not been observed.

Viewing the electrical installation for the bathroom lighting from above, it was noted that no fire protection has been installed for the halogen down-lighters, and the heat generated by the lighting units is also being wasted through the roof. The head of the staircase is another area of the attic where the design work has not been fully thought through, both in the fitting of the staircase and in terms of the headroom. The top step represents a serious trip hazard.

The boiler has been installed within the attic and is generating a large amount of heat within the area of the house which least needs it, since the heat from the rest of the house rises to warm the attic anyway. The addition of an over-sized Velux window on the southwest facing part of the roof will also tend to overheat the attic space on sunny days and lose heat, particularly at night. A dormer window would be more appropriate in this location, because it would present a larger glazed area to the lower winter sun, allowing solar gain in the winter months, reduce exposure to high summer sun and reduce night time heat losses.

The attic area, if required for use as accomodation, needs considerable remodelling. It would be better to begin again with a new conversion, rather than try to work with the existing.

Heating and hot water

The house is heated by a Worcester Bosch ‘Highflow 400’ combination boiler, with heatstore. This is a good modern boiler and it seems to be working well, although it appears to be over-sized for the house. If solar hot water replaces some of its function, it may be that a smaller boiler would be more efficient, although further investigation would be needed to assess this.

Heat is being lost between the boiler and the point of use through unlagged pipes, which pass outside the building’s thermal envelope and are buried in walls in places. There is a small leak on the connection to the hot water tap in the bathroom basin. 

Bedroom One

This room is on the north side of the house and has a large glazed area above a single skin (uninsulated) bay. There is also a low level of insulation in the loft above, so the thermal performance of this room could be improved by adding insulation to the bay wall and by upgrading the loft insulation.

Bedroom Two

Large amounts of heat are lost from the over-large glazed area of the bay window. Equally, as the elevation is southwest facing, there will be excessive solar gain on sunny days. The glazing units fitted to the uPVC structure are built with a spacer of 12mm thickness, and so are less efficient than windows with the recommended 16mm spacer. Evidence of structural movement is visible in cracking to the right of the bay.

Bedroom Three

This room is warm from solar gain due to the southwesterly elevation and the presence of the hot water pipes from the boiler above, which run within a box on the wall. Here the window units are built with a 20mm spacer, which is also less efficient than the 16mm standard. The window does not seal completely since the catches need maintenance.

The stairs which lead to bedrooms three and four do not comply with building regulations and present a serious hazard.

Bedroom Four

This room is cold and a combination of factors is likely to be responsible. The front elevation is northeast facing, therefore the oriel window fitted is totally inappropriate for its location: it presents an area of over 2.5 times the area of the original window aperture (which is already large for the northerly elevation of a small room) and the insulation installed in the structure is almost certainly minimal by any standards.

No insulation could be observed above the ceiling of the garage (which is at ambient external temperature) and this will be another cause of the cold bedroom. It is believed unlikely that the cavity wall on the westerly elevation has been insulated and there is no thermal mass on the internal walls of the room. These would help to maintain a stable background warmth.

Study/Bedroom

The outward opening door is believed to be a hazard which should be attended to in the course of future works. This room could be redeveloped in the future, as en-suite facilities for the two adjoining bedrooms, for example.

Bathroom

In this room there is another non-closing window, also fitted with 20mm glazing units (see Bedroom Three, above). There is no extractor fan, air brick, or form of venting other than the window. Venting is a Building Regulations requirement in a shower room. The lighting (halogen down-lighters) has been installed without the required fire prevention measures.

Conservatory

Two small excavations were made in order to examine the wall structure and footings, which revealed a course of concrete block on the outside and three courses of soft bricks on the inner face, laid on a foundation of concrete (500mm wide by 180mm deep). Subject to confirmation from a structural engineer, it is considered that this an inadequate foundation for any extension which might be planned.  It was noted that although a membrane has been installed under the floor, it is below ground level, and there is no 'french drain' around the base of the low wall. It is also noted that the downpipe for the main roof is routed into the corner formed by the conservatory and the rear wall of the kitchen extension, where the water butt is situated. The downpipe may be inadequate for the now-enlarged roofing area and may be backing up and soaking the ground near the water butt. This could be the cause of the low-level ingress of moisture noted by the clients, but further investigation is needed on a wetter day.

At the rear of the conservatory, below the bay window, a section of plasterboard near the centre of the doorway was removed to determine the dimensions of the timber members used in the stud framing. The members provide support for the bottom of the bay above. The timbers are 75x50mm and their inadequacy for the purpose is shown by the downward bowing of the doorway head.

A pair of 15mm copper pipes run the length of the studding and are possibly the central heating feed and return.

If a new extension is being built to replace the conservatory, consideration should be given to the installation of solar hot water or photovoltaics on the extension roof, as it is a large area on the south-facing side of the house.

Dining Area

This area will be hard to keep warm in cold weather due to the thermally inefficient french doors, which open directly into the conservatory. In the current arrangement, these doors should be upgraded to external-type doors for extra security and better thermal performance. At the least, they should be draught-proofed all around. Once again, the halogen down-lighters need to made compliant with fire regulations.

Kitchen

As before, the down-lighters are non-compliant, but this did make it easy to see that there appears to be no insulation installed in the recently built kitchen extension roof. This is a major flaw in the building, in energy efficiency terms.

The concrete floor divides into three areas: the original kitchen floor, the side extension and the rear extension. Three small holes were excavated in the concrete subfloor with the use of hand tools and a small power tool. The rate of progress was slow, as the concrete is very hard and the thickness is approximately 150mm. In order to install underfloor heating in this area, it would be necessary to remove the concrete with the use of heavy power tools, possibly even a mini digger, before proceeding further. As you will appreciate, considerable disruption of the household would be caused. It would also be necessary to check that there are no services buried in the subfloor, although there is currently no reason to think that there are, as services seem to enter from above. 

On balance, it is considered that the use of a mini digger would be preferable in terms of speed and health and safety. It might be possible get access via the garage, since the utility area/rear garage wall needs attention anyway.

Utility Room

The utility room is acting as a buffer between the kitchen and garage, although the doors are not air tight. It is difficult to see where the services are running, as many were boxed in when the extension was built. It appears that the original exterior wall has been dismantled and the stone re-used for the exterior of the new extension.

Garage

There are several issues to be addressed here. Firstly, the fire regulations obligations have not been resolved regarding the ceiling and the inner walls. The plasterboarding to the ceiling is only a single layer with gaps, which cannot comply. A second layer needs to be applied, with the joints staggered and then plastered. The same is true of the two internal walls and attention should be given to making sure that the exposed timbers of the staircase are properly enclosed in the process. The internal door needs to be replaced with a fire door and draught sealed. The gas meter has been boxed in, making access difficult to the shut-off lever and the pressure test, and for inspection of the security tags.

Outside

There is a potential problem with bridging of the damp-proof course on the more modern parts of the building, where block paving has been brought up very nearly to the same level as the damp-proof course.

There are cracks around the window and door frames, and the junctions have not been sealed correctly, so there will be high air infiltration. 

Next

From the point of view of making the most of your property, in the short term, your priorities should be as follows:
- Improve the structural stability of the bay window. A structural engineer should be employed to advise on the best approach.
- Put right minor faults and earlier improvements to your home which do not comply with building regulations, particularly those which are an immediate hazard. An architect will be able to advise more fully on areas requiring work for building regulations approval.
- Improve the thermal performance of your house by making the roof, windows and doors more airtight; and by installing cavity wall insulation in the side extension.

We would be happy to provide any of these services.

In the longer term, remodelling your attic would bring significant thermal improvements and increase the size of your home, but is disruptive work. To gain useable space with less disruption in the first instance, you might prefer to begin with improvements to the conservatory while you work through designs for attic improvement. There are also redevelopment works to the kitchen and garage which would bring thermal and practical benefits.

You should begin putting together in writing your thoughts on the advice we have given you, including any questions you have, and your priorities and aspirations for the house. This will form the basis of a design brief for further work, which we will develop with you. With a design brief, we can progress on to planning a schedule of works and effectively put the work out to tender, whether by us or by other contractors.

Simon Lewis

Proposal

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