Bemak

I hacked a bit of render off a few years ago to see how labour intensive it would be. Found 3 layers of render had been added over time and it was very difficult to remove, often pulling stone with it. So I repaired the patch I removed. The intention is to render the house completely in the end. I had originally looked at dry lining internally but we've opted to go for 40mm of insulating lime render instead. I was told that over insulating internally could be a bad thing as the walls would sweat behind the gutex board.

Thanks for this link. Think this is probably the better solution for us. The reason I ask if MVHR can be run as extract only is because I don't want to run the risk of being sorry after the fact for not installing it. I assume I wouldn't be

Just thinking. A MEV system utilising trickle vents in windows would be a cheap to run solution that would do what I want which is to extract moisture. I'm used to living in older houses to the heat recovery aspect is probably lost on me. Can MVHR units be run as extract only if required?

Thanks John. That's interesting. Hoping to achieve that level of airtightness. I guess once the envelope is sealed we could carry out a test to see where it's at before deciding on MVHR. As you say, I'd probably be happy with a MEV setup. dMEV isn't really an option as I don't want to go coring 600mm thick rubble stone walls. I'm reroofing the house so I'll be able to add vents to the roof for a MEV system

yes we're putting in a new insulated GF slab which should make a big difference. the external walls are sand and cement render unfortunately. we looked into the possibility to taking it all off and replacing it with lime but it's a non-runner because of a) the prohibitive cost and b) as we're in an exposed area in the west of Ireland, lime render doesn't particularly suit the driving rain that we can experience for weeks on end. so the only direction for the walls to breathe will be inwards. we've stripped off the internal render however and thankfully the walls are quite dry as is. I'll install a french drain around the perimeter of the the house as well which should help with moving ground water away from the base of the walls. it's all we can do really

oh absolutely. I'd likely oversize it to be safe

As posted elsewhere, I have started renovation works to an old stone farmhouse (150sqm) which involves the addition of a two-storey extension. We've decided to go down the route of UFH on both floors which will be run with a traditional oil boiler for now. We've allowed provisions for a HP in the future. The heating will be supplemented by a back boiler in a solid fuel stove. As the existing stone walls will be rendered internally with an insulating lime render to allow moisture to escape - I want to install a good ventilation system that will help to extract moisture from the house. The preference is for the unit to go in a warm attic, from which I can duct all the rooms. As the layout of the house is quite simple, the routes are relatively straightforward. In researching MVHR units, I stumbled upon Nilans Compact P2 unit which combines the ventilation system with the HW Tank which has it's own heat pump to generate hot water. On paper it sounds like a nice system - but it might be overkill for my situation. I suspect installing separate systems would be more cost effective. I would be curious to hear peoples thoughts on it, particularly if you installed a MVHR unit in a similar refurb scenario. At this point I wouldn't know which manufacturers would be considered 'premium' and which would be 'budget' so even to get recommendations in that regard would be great.

In the middle of refurbishing an old farmhouse at the moment and am currently working out service routes before the new slab goes in. I'm proposing to locate an external boiler about 20m from the house - the pipework will be 26mm pex pipe (10mm insulation) which will be run inside a 110mm Wavin pipe - all of which will be buried about 600mm below ground level. I appreciate that some element of heat loss will occur along the way - but as we're proposing UFH in the house, the reduced temperature shouldn't affect things too much. Before I lock this in, just wondering if anyone else has done something similar and if so, how has it worked out? Thanks! *update - apologies, I just realized that I posted about this already. Please ignore!*

thanks for the link!

As posted elsewhere, I've embarked on the refurb of an old 2-storey farmhouse. As part of the refurb I'm going to install a MVHR system to ensure that moisture and condensation is adequately dealt with. I'm also installing a new insulated floor slab with a radon barrier and sump. I was going to run the vent from the sump out under the slab and bring it up in a nearby flowerbed to conceal it. The idea is that I would just put a cowl on it and let it vent naturally. However, in a lot of instances locally, the radon vent is brought up to the perimeter footpath and just capped - then, if necessary, the cap can be removed and a duct with a fan can be installed to vent the sump. My issue with that approach is that I don't want the potential to have a vent running up the side of the house when we've been so careful to conceal all the services to date. However, as we are going to be installing a MVHR unit anyway, I assume it's highly likely that we'll never need to vent the radon sump in the future considering the house will be so well ventilated? The reason I ask is I may just revert back to the standard solution of capping it on the footpath as opposed to bringing it up in a flowerbed as currently planned.

thanks for all the replies on this. I've been distracted with demo starting on site. finally! what are peoples thoughts on UFH for upstairs as well?

thanks for this!

I recently came across 'over floor' heating systems which are essentially an underfloor heating system in a 30mm screed - the idea being that the system is much closer to the surface of the floor allowing for quicker response times while generally running at lower temperatures. I spoke to a supplier about it and they said the following which I thought was interesting "the system achieves a typical operating energy reduction of 50% daily compared to heating the same space using Under Floor Heating". "Conservation of energy on a daily basis sets the ground work for affordable heating and sustaining the building, the most significant feature of Over Floor Heating systems is the remarkable increase in comfort created by operating the system using water at body temperature". All sounds great. I'd be curious to hear of peoples experiences using such a system as I wouldn't be opposed to trying it on a refurb I've started.

just a quick query on a detail I want to ensure is correct. i'm planning to construct a cavity wall extension to the side of an existing two-storey farmhouse. the new extension will replace an old stone extension and we've yet to determine if the stone extension was keyed into the stone of the main house. In any case - I was wondering how best to detail the junction between the new blockwork and existing stonework to prevent any water in the stone wall from getting into the inner leaf (as per the crude diagram below). Is a vertical DPC the best bet or is there a better way of doing it?

that's a great point regarding the soak away in the middle of the run. Thanks Nick!