Old Cottage Restoration + Extension Project

[Cpd]

10 hours ago, JulianB said:

That does make sense in my mind, as you have maintained the ventilation aspect and upped the drainage ability of the ground immediently underneath. Could I ask what you've done to the walls?

So far I have only done the small walls (1m high) upstairs, it’s 1.5 story house. These were framed out with calotex within the frame and more over the top. There is a ventilation gap behind the insulation that links into the overall wall ventilation. I am procrastinating over the upstairs gables and all the walls downstairs...... the project has ground to a standstill at the moment due to family issues so I can procrastinate a good bit more ! The walls are very uneven  and it would be a massive job to level and smooth them out so framing and insulation would be my first choice, however I would need to add in some additional ventilation in some areas to be sure they would always dry out should condensation be an issue. 

[Simplysimon]

don't know wheher you've read this item, sounds as though it should be pertinent though

[JulianB]

14 hours ago, jfb said:

 

I think it was a few things. I had a few architects come around at the beginning and one who had some experience of renovations of this type suggested a concrete floor for cost reasons and after a general assessment of the house not being too damp as it was. He also pointed me in the direction of cheaper woodfibre boards than I was considering. (he was Charlie Luxton from a programe called 'Building the dream' if that means anything).

I think it is undeniably cheaper to use a concrete floor as it uses more conventional materials (I was comparing limecrete and expanded glass sub base against concrete slab and type 1). Also I had quite a large area to do so used a pump for the pour which might be possible with limecrete but not as straightforward.

It did also leave the floor finish more open as you don't have to think about permeability of tile/floor finish. In fact for a new extension to the house I ground the concrete slab down for a polished finish which wouldn't have been possible with  a limecrete slab.

I also read up on some issues with UFH and limecrete floors.

 

I would say that my place isn't in an exposed situation so that is to my advantage.

 

I ended up with 60mm steico woodfibre board and 20mm on window reveals. In theory the 60mm of woodfibre board doesn't meet building regs but my thinking is that the more insulation the higher the risk of interstital condensation. I suspect this wall buildup performs much better in practice than theory might suggest. Room size is also a consideration when using IWI.

 

MVHR is another thing that I wasn't 100% I was going to install but the more I read the more I decided to go with it. Also I think the architect had the assumption that it would be necessary. I did go pretty overboard with airtightness detailing in the end and got a reading of 1 ACH/hour so I am glad I went with MVHR. Overall I have been very happy with the results - house temperature remains very stable without much heating needed and we have barely used the radiators upstairs.

 

Charlie Luxton was your architect?? I've seen every episode of 'Building the dream' so I feel I know him pretty well now hehe! In my old house I had installed a limcrete and Glapor sub base floor, finished with the original flag stones which really worked efficiently in combating any damp issues (to put it into perspective the adjacent neighbours couldn't leave furniture in the same position for too long because of the damp patch it would create on the floor!).

 

Did you say you put a layer of wood fibre board under your concrete slab? Did the slab run all the way to the walls or did you leave a ventilation gab? I might need to research UFH & limecrete compatibility again as I can't remember there being major concerns but I could have forgotten!

 

Your ach/hr of 1 is VERY impressive!  Can I ask what type of house it was and if you have any pictures into the level of detail you went to, to achieve that sort of result? Any tips would be greatly appreciated!

 

12 hours ago, Simplysimon said:

don't know wheher you've read this item, sounds as though it should be pertinent though

 

Ah yes...I had actually book marked this blog and gone through their various blog posts...interesting Diasen product! I was surprised that they only offer it in spray form by a contractor, but it definitely sounds hopeful! They seem to suggest that it took exceptionally long to dry out, which might have contributed to the condensation and mould they were seeing in areas. Definitely worth a thought!

[JulianB]

23 hours ago, PeterStarck said:

I haven't increased the DHW temperature above 45C in the, nearly, two years we've lived here. The flow rates seem fine but we do have aerating showers and taps so I don't know whether the aerating effect masks anything.

 

Thanks! One other question I had when going through your blog actually...what did you think of the reed beds for the drainage discharge? We're installing a sewage treatment plant do not have space for a drainage field. There is not watercourse closeby, and we're wondering wether getting a permit to discharge into a borehole would be the best solution, or potentially opt for something like the reed beds if they don't take up too much space, leave odours etc?

[Gone West]

1 hour ago, JulianB said:

 

Thanks! One other question I had when going through your blog actually...what did you think of the reed beds for the drainage discharge? We're installing a sewage treatment plant do not have space for a drainage field. There is not watercourse closeby, and we're wondering wether getting a permit to discharge into a borehole would be the best solution, or potentially opt for something like the reed beds if they don't take up too much space, leave odours etc?

If at all possible I would prefer to have a deep bore soakaway. When we installed our treatment plant, ten years ago, discharge permission wasn't required if your property is not over a certain type of aquifer. I can't remember the details now. The reed bed system we have is high maintenance and there are safety issues when maintaining it but at the time it was all BC would accept. More recently the BCO allowed our neighbours to have the outlet from their sewage treatment plant flow into another tank which was filled with plastic filter media and from there it flows into an ordinary soakaway. There are also trickle filter systems which can be used for tertiary treatment before flowing into an ordinary soakaway.

[ProDave]

1 hour ago, JulianB said:

 

Thanks! One other question I had when going through your blog actually...what did you think of the reed beds for the drainage discharge? We're installing a sewage treatment plant do not have space for a drainage field. There is not watercourse closeby, and we're wondering wether getting a permit to discharge into a borehole would be the best solution, or potentially opt for something like the reed beds if they don't take up too much space, leave odours etc?

Where does the old system discharge to?

 

On a new build, not having a drainage solution would stop you getting a building warrant so would stop you building (at least it would in Scotland)

[JulianB]

11 hours ago, ProDave said:

Where does the old system discharge to?

 

On a new build, not having a drainage solution would stop you getting a building warrant so would stop you building (at least it would in Scotland)

 

Hi Dave,

 

I can see the direction it heads off to, but nothing above ground to give any real indication! It's pretty close to our boundary and looks like it goes off to an adjacent farmer's cattle field...potentially a soakaway or drain field, but it is very old (previous owner who had the property for ten years before us also had no clue!). Our new system will be roughly within 10 metres so should be considered part of an existing system.

 

11 hours ago, PeterStarck said:

If at all possible I would prefer to have a deep bore soakaway. When we installed our treatment plant, ten years ago, discharge permission wasn't required if your property is not over a certain type of aquifer. I can't remember the details now. The reed bed system we have is high maintenance and there are safety issues when maintaining it but at the time it was all BC would accept. More recently the BCO allowed our neighbours to have the outlet from their sewage treatment plant flow into another tank which was filled with plastic filter media and from there it flows into an ordinary soakaway. There are also trickle filter systems which can be used for tertiary treatment before flowing into an ordinary soakaway.

 

Thanks for the advice! What sort of maintenance and safety issues are we talking about re. reed bed if  you don't mind me asking? We've submitted an application for some advice from the environmental government agency, hopefully they'll keep the soakaway option on the table.

[ProDave]

5 minutes ago, JulianB said:

 

Hi Dave,

 

I can see the direction it heads off to, but nothing above ground to give any real indication! It's pretty close to our boundary and looks like it goes off to an adjacent farmer's cattle field...potentially a soakaway or drain field, but it is very old (previous owner who had the property for ten years before us also had no clue!). Our new system will be roughly within 10 metres so should be considered part of an existing system.

 

You need to do some investigation, even if that means digging to find the pipes and where they go.

 

If it heads off to an infiltration field under the adjacent land, what is to stop you continuing to use that with a new treatment plant if it still works?

[JulianB]

Just now, ProDave said:

You need to do some investigation, even if that means digging to find the pipes and where they go.

 

If it heads off to an infiltration field under the adjacent land, what is to stop you continuing to use that with a new treatment plant if it still works?

 

The reason i didn't really do a great deal of investigation was because the new extension will be lower than the current septic tank soil pipe run, and hence we would have to look into pumping sewage up a story. If we bite the bullet and re locate it to the other side of the garden, it can be sited lower and remain gravity fed, whilst also be upgraded to a sewage treatment plant and hence not have any issues in the future should we ever decide to sell.

[ProDave]

A site layout plan would help at this point.

[JulianB]

5 minutes ago, ProDave said:

A site layout plan would help at this point.

 

Presto! I've attached some really rough Sketchup screenshots from the last time I played with the external landscaping to give you an idea of the level change...

[ProDave]

Some dimensions would help on that layout plan.

 

My gut feeling is there is not enough space on your own land for a treatment plant and the soakaway for it.  I am near certain that existing septic tank will drain to an infiltration field to the east, perhaps partly under your land but almost certainly extending under the field. 

[JulianB]

27 minutes ago, ProDave said:

Some dimensions would help on that layout plan.

 

My gut feeling is there is not enough space on your own land for a treatment plant and the soakaway for it.  I am near certain that existing septic tank will drain to an infiltration field to the east, perhaps partly under your land but almost certainly extending under the field. 

 

Thanks for that. What dimensions would you like me to include...the current distance from septic tank to our nearest boundary is 7 metres (east on drawing). Yes I would tend to agree that there would be no space what so ever for an infiltration field. I've had a chat with the friendly farmer and he seems open to the idea of striking a deal to place a drainage field in his land...however there are cattle around for most of the year, so that seems like a dead end. Not sure what sort of floor area a bore hole occupies, but thinking this could potentially be an option? Only other thought that pops into my mind is us actually buying some land of the farmer (if he was willing) and then place a drain field on that...from chats with afew suppliers, it seems anything from 50-100m^2 would be needed

[ProDave]

You would have to check the English building regs (I am only up to speed on the Scottish ones) but here you have to keep an infiltration field 5 metres from your boundary and 5 metres from a building, so there would be no land available in your own plot I suspect.

 

If the farmer is willing then that is your solution. I don't see the cows as an issue, cordon off the corner with an electric fence while the work is being done.  We did a similar thing in a day with a competent speedy digger driver.

[JulianB]

Thanks, I ll have a good look through the regs. My only concern re the cattle if we weren’t able to purchase some one off him would be the cattle traffic (hoof traffic?) compacting the ground and leading to issues with the drainage field ?

[Gone West]

11 hours ago, JulianB said:

What sort of maintenance and safety issues are we talking about re. reed bed if  you don't mind me asking?

The reed bed system we bought came with common reed (Phragmites australis) plants. These grow vigorously to around 8m high and unless there is sufficient space need cutting down to an acceptable height throughout the year. I found out later that other types of water plant are suitable as long as they have a rhizome root system so we replaced the reeds with irises which only grow 0.75m high. Apparently the bacteria that continue to breakdown the effluent live on the rhizome root system. The beds have to be cleared out every 3 to 4 years depending on plant growth which entails removing the plants and silt. The plants have to be split up and then replanted and the excess plants disposed of.

If the ground conditions are suitable you may not need a very deep borehole. Ours is 110mm diameter but unfortunately even after drilling 47m down to the chalk only found water bearing geology.

[Gone West]

10 hours ago, JulianB said:

My only concern re the cattle if we weren’t able to purchase some one off him would be the cattle traffic (hoof traffic?) compacting the ground and leading to issues with the drainage field ?

Around here any pipework under agricultural land has to be 1m below the surface to prevent damage to the pipework by any future deep ploughing. I can't see the activity of any cows affecting pipework 1m down.

[JulianB]

21 hours ago, PeterStarck said:

Around here any pipework under agricultural land has to be 1m below the surface to prevent damage to the pipework by any future deep ploughing. I can't see the activity of any cows affecting pipework 1m down.

 

i thought there was a maximum depth of 0.75m that a field drain could be...if I can go to 1m and not have any adverse affects from the cattle it would be brilliant! Only other small issue is that there will be a festival (Fairport) on 1st a year so maybe a coupe of caravans, although I could probably lay along the boundary line to avoid the chances of traffic...

[scottishjohn]

Is this same house as you are referring to in ASHP thread?

 have you PP to convert as your  drawings above?

have you got costings 

 

[JulianB]

42 minutes ago, scottishjohn said:

Is this same house as you are referring to in ASHP thread?

 have you PP to convert as your  drawings above?

have you got costings 

 

 

Morning John!

 

Yep, PP obtained to convert into the scheme on pg1 (subject to the Building control drawings). We're still waiting for the building control drawings to get accurate quotes from the builders we have approached, however they have given us very rough estimates to get us to shell afterwhich point we will most likely take over...we'd also be looking to tackle the demolish and a few other aspects ourselves...

[scottishjohn]

31 minutes ago, JulianB said:

 

Morning John!

 

Yep, PP obtained to convert into the scheme on pg1 (subject to the Building control drawings). We're still waiting for the building control drawings to get accurate quotes from the builders we have approached, however they have given us very rough estimates to get us to shell after which point we will most likely take over...we'd also be looking to tackle the demolish and a few other aspects ourselves...

Its such a major revamp I do not understand your view on how to treat the cottage itself 

It surely has to be a bare wall rebuild at same time sorting all possible future damp  problems 

looking at piccie  you are doing alot of changes to front of cottage to tie the 2 storey extension on to it and digging out right next to probably invisible foundations of old cottage  to make new ones for extension --alot of underpinning may be needed to that side of house or very serious retaining walls.--you better make sure they are going to warranty the exsisting cottage integrity  after their work 

looks like  2-  2.6M DROP  around alot of the exsisting cottage to then be built back up with big retaining walls around the plot my guess it will be 3m+ in places by time you include founds for new extension

hope you got a good SE involved at this stage 

 the cost of doing proper tanking job of cottage will be small in total cost of job

 

 

Edited January 20, 2020 by scottishjohn

[JulianB]

Yeah…it definitely isn’t for the faint hearted…and hopefully it won’t be our downfall! We do intend on addressing all issues with the cottage at the same time; stripping back walls to bare stone, installing French perimeter drains, upgrading windows, floors etc.

What we’ve tried to exploit when proposing this extension is the lay of the land; from the front to the back of the cottage, the land falls away quite significantly (and continues to fall passed our plot)…the existing extension (which sits on the back of the lodge) is higher than outside ground level by up to a metre, and already incorporates a 1metre drop in FFL relative to the original lodge. Our plans are to bring that FFL in-line with the lodge, which buys us an extra metre prior to looking for that additional storey beneath. We will then excavate half of the rearward elevation, to a depth of ~1.7m which will get us to the underside of the floor slab (granted trench foundations will be deeper than this by quite a bit). The footings of the cottage are 0.95m in the two test digs I’ve performed, which would leave us with a further 0.75metres. Our SE has spoken about excavating part of the internal floor space of the lodge to avoid the need for the underpinning to also be retaining, however we are still working on a solution which wouldn’t result in the front wall needing underpinning. At present the underpinning will span just over half of the rearward elevation (~5metres) and slightly round the corner of that portion of the lodge, which isn’t too bad. 

Most of the new extension should be above ground (to keep tanking to a minimum). The proximity of the trees doesn’t help either…but then again all these factors are what enabled us to buy the cottage at a price we could afford.

 

 

 

[scottishjohn]

at some stage you need to ask the BC man what happens if the original wall does collapse when carrying out this conversion 

A friend of mine was warned  in a barn conversion he was doing that if the wall collapsed

-then the PP would be withdrawn   and rebuilding it even with same stone in same manner would not work 

as its a listed building and it would then be classed as a ruin and no rebuilding would be  allowed

-you could end up with a ruin you can do nothing with 

 not trying to scare you --just something to consider

that could  be a different scenario of course,as it was a change of use as well as being listed --but worth asking the question beforehand of one of your professional advisors

[JulianB]

4 hours ago, scottishjohn said:

at some stage you need to ask the BC man what happens if the original wall does collapse when carrying out this conversion 

A friend of mine was warned  in a barn conversion he was doing that if the wall collapsed

-then the PP would be withdrawn   and rebuilding it even with same stone in same manner would not work 

as its a listed building and it would then be classed as a ruin and no rebuilding would be  allowed

-you could end up with a ruin you can do nothing with 

 not trying to scare you --just something to consider

that could  be a different scenario of course,as it was a change of use as well as being listed --but worth asking the question beforehand of one of your professional advisors

 

Thanks John! Will definitely ask BC man what would happen in that scenario...one of the conditions on the PP is that we have to provide a method statement re. how the wall will be demolished, so I'm imaginging they're covering that base through that avenue. Reminds me of one of the grand designs when a good portion of a castle wall came down...I think they rebuilt it out of blockwork!

[Duke147]

On 16/01/2020 at 19:38, Cpd said:

So I have an old stone cottage with 700mm stone walls and 1000mm gables. I dug up the floor down to just above the footing base , dug in various land drainage systems to allow any water to escape should it get in there, filled the area with the stuff railways are build on (200mm) (golf ball sized stones.) compacted as I went but still allowing full drainage over the whole area. Capped it of with cement, but left a 50mm gap around the outside.  put two layers of DPM down, the first was semi sacrificial but in reality it will be fine. Laid 100mm of reinforced concrete (BIG MISTAKE) as I should have put insulation down...... again I left a 50mm gap round the edge and filled with pea gravel. Insulation will be 90mm  PIR, I am hoping to put WUNDA   - Wundatherm Premium+ Board – Underfloor Heating  boards down and then final floor coverings. The DPM will go up the wall and join up to whatever I have there. I will frame out the whole house and there will be a vented void between the stone wall and the framework. Insulation between and over stud-work, battens and plaster board. The building is bone dry with absolutely no sign of water coming up or into the walls even though there is no damp proof course. The 50mm drainage gap filled with pea gravel around the walls was a precaution as the exterior ground level is higher than my final floor height. However because it’s a 700mm double stone wall with a rubble middle it was not an issue as any water that does get in goes down the middle of the wall and then can exit through the huge drainage area. I regret not going deeper and if I knew then what I know now........ but hay ho. I don’t think 90mm of PUR is good but it will one day be a holiday rental and the losses in heat downwards will be compensated for by it making money. (limited head room means a MAX of 90mm PIR plus the WUNDA board)  I am hoping that UFH run from the ASHP will provide a really nice level of comfort. There will be a WBS for the caveman enthusiasts. Upstairs will be either fancy radiators run of the ASHP or just a couple of electric heaters on the wall for top up. 
 

Did not know this, I have assumed it was so poor I did not take it into consideration, however it really does help with stability of temperature as the house even unheated and with just the upstairs insulated stay very stable. I have no issues with glazing as the house faces east so only gets a bit of sun in the morning due to a hill. 
 

anyway a bit of a ramble but just another perspective. 

Hello all,  we are a few years down the line from the start of this topic, but I found this thread very pertinent to a project I will soon be taking on hopefully, if the purchase goes ahead.

My issue is a listed building with suspected solid walls (no cavity) and within green belt.

 

The quoted post above by Cpd seems to my mind to be "my preferred solution" after my limited research and it is by no means the only solution.

 

There is a great document on this situation by Historic England HERE btw.

 

It defines what the original poster has been hinting at all along in his replies to others, and that is the long to very long term potential hazzards of fully waterproofing the inside without paying attention to the external wall which nobody has yet paid the correct attention to in my opinion.

 

But, Cpd has pointed out a way of mitigating the ground water and the salts that could harm the external wall over time and it seems to make sense to take the ground below the slab as low as possible or as low as required, so as to aid the dispersion of water at the base of the outside wall.

 

Cpd pointed out the mistake of capping off with cement at the wrong stage, so future readers should take note.

 

It would be nice if @Cpd could update the forum as to his solition working if he is still about?

 

As for the 50mm perimeter with pea gravel, my choice would be PIR board cut into strips to shutter off the perimeter/outside wall, prior to pouring concrete to the required height.

This shuttering will break the cold bridge between slab and outer structure.

 

So my build up of floor would be something on the lines of:-

 

*Install french drains to the full perimeter to a height below the internal finished floor level

*dig out original concrete floor to depth to be determined

*Insert perforated drainage pipes of 4" or 6" running away from th property (downhill)

*Take those pipes beyond the external wall that they fall towards if possible (and into the external french drain?)

*Lay large golf ball sized hardcore base over the perforated drainage pipes

*Lay a softer edged product to protect DPM from being punctured ie builders sand

*Lay DPC and take it well up the walls ie minimum of 1m (I believe rising damp cannot rise over 1m)

*Lay correct depth and type of under slab insulation 

*Lay concrete pad to correct thickness

 

From there, I will consider further on weather to install a cavity or not between the external wall and insulation to the inside walls depending on what I find during investigations.

I will also revisit the Historic England document several times to consider the options mentioned, and as they say, it may well be a hybrid approach which may depend on which elevation faces the differing climatic conditions.