Refurb: getting the most out of insulation

BoardsMember

Hi folks.

We are planning a renovation, initial stages. House is a 1920's property, end of terrace (single garage at the terrace end), red brick to front, suspended timber floors, roof is the original with no barrier or insulation, just old crumbling render on the underneath of the tiles. I put rockwool in attic a few years ago between the joists. Windows are decent double glazed so will stay though we probably need to re-seal as some of the silicone (or whatever) is peeling. We have a front porch. Heating is a modern gas fired condenser boiler, rads & plumbing are all modern, replaced 8 years ago though will prob put in a bigger hot water tank, and possibly move to attic.

We need to fully rewire, and plan to build an extension (perhaps to replace garage on gable end). In doing so I want to make sure we allocate enough budget to ensure a cosy finished product.

Main questions relate to the following:

1. Floors in sitting room and dining room are suspended with several feet space below...it's very draughty at the moment. I have read up on various options. Not too keen on ripping up the existing floors to insulate between joists, tape etc, then re-lay new boards. Have a feeling it would be very costly on the labour front. Could I instead put insulation on top of existing floor, then new boards on top of that? Ceilings are high, so not a huge issue to lose height in the rooms but wonder how much loss of height we would get with acceptable insulation?

2. Wall insulation.....I understand external is more effective. The reception rooms are on the gable end and run front to back. The front sitting room has red brick outside so we can't insulate that wall externally. It is south facing, gable end is west facing. With that in mind, should we go internal insulation in both rooms? Or could we do a mixture, where we externally insulate the west and north facing walls, and internally insulate the south facing? If we insulate the floors inside and the walls inside, would we get a pretty good outcome if we tape floor to wall, wall to ceiling etc. Or are we better doing some externally?

That's it really. Any information or recommendation on approach or material thickness etc would be appreciated.

Thanks,

BM

tedimc

Re your floors - could you cut a small section out or lift a few boards and then access the rest of the floor from underneath?

I would be reluctant to insulate on top of them as you will have issues with external door heights, internal steps, etc - as well as perhaps having to check the floor structure for rot.

Re the walls - my dad done up a 1890s red brick last year. He got his insulated internally and it worked out well. However, he was very limited with insulation thickness as he wanted to retain the original plaster covings, etc. I think in the end they managed to take them down and put them back up again later, with just some minor remedial works.

However, he needed to re-plaster his walls inside anyway as they were in bad shape due to years of re-painting, wall papering, etc.

The guy he used had a lot of experience with those particular types of house.

BoardsMember

tedimc wrote: »

Re your floors - could you cut a small section out or lift a few boards and then access the rest of the floor from underneath?

I would be reluctant to insulate on top of them as you will have issues with external door heights, internal steps, etc - as well as perhaps having to check the floor structure for rot.

Re the walls - my dad done up a 1890s red brick last year. He got his insulated internally and it worked out well. However, he was very limited with insulation thickness as he wanted to retain the original plaster covings, etc. I think in the end they managed to take them down and put them back up again later, with just some minor remedial works.

However, he needed to re-plaster his walls inside anyway as they were in bad shape due to years of re-painting, wall papering, etc.

The guy he used had a lot of experience with those particular types of house.

Thanks a ill for the input. Yes, you're probably right about the floor height, will do everything we can to keep as is. With having to re-wire I think internally insulating is the best option. We don't have any really nice coving, so could get some new/simple ones and just rip out what is there.

I'm still slightly tempted to try to include external insulation but not sure how to.