Moira Niedzwiecka Posted October 27, 2017 Share Posted October 27, 2017 Hello All, Our house is a 300mm closed panel timber frame insulated with cellulose. This is the make up of the walls and the roof. Externally we will have a natural slate roof, walls render & ironstone. Has anyone with a similar construction had any issues with an internal TV aerial? Will we still be able to get a signal through this construction? It has only just occurred to me. I would be grateful for any help. Moira Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 27, 2017 Share Posted October 27, 2017 If you're in a very good signal area, then you might get away with an indoor or loft fitted aerial OK, but I suspect you may struggle. We've found that our house, which has a very similar construction, attenuates high frequency signals a fair bit, so, for example, DAB radio won't work indoors, but FM radio does, just about. Mobile phone signals are very weak in our area, as are terrestrial digital TV signals, and neither can be reliable received. Terrestrial digital TV frequencies are quite high, and may well be attenuated to the point where an indoor or loft aerial won't work. You can feed cables through the wall for an external antenna, but it's a bit of a fiddly job. I did it using a specially made up long 6mm diameter drill, to drill the pilot hole right through the wall, then a 20mm hole saw either side. With a lot of patience and a bit of plastic turned up to form a pointed bit that was a tight fit in the end of a bit of 20mm plastic electrical conduit, I managed to fiddle around and get a bit of conduit through the wall, and sealed it on either side. I then ran antenna cables through this, and sealed it up around the cables at either end. This worked OK, but was a bit fiddly and time consuming, as it's not easy to feel for the hole on the other side when poking something though 300mm of cellulose filled wall. Link to comment Share on other sites More sharing options...
Moira Niedzwiecka Posted October 27, 2017 Author Share Posted October 27, 2017 Jeremy, thank you for your reply. We are going to have to work out how to get the in roof PV cables and the cables for the alarm & external lighting through as well. We also have to vent the soil stack to the outside too as we are the only ones on this sewer run. We didn't really want an external SVP so will have to go out through the gable end wall. Link to comment Share on other sites More sharing options...
Temp Posted October 27, 2017 Share Posted October 27, 2017 35 minutes ago, Moira Niedzwiecka said: Has anyone with a similar construction had any issues with an internal TV aerial? Will we still be able to get a signal through this construction? Very much depends on a bunch of factors such where your house is, how far away the transmitter is, any trees or hills etc. I used foil covered insulation in our loft and obviously that blocked the signal. I replaced a few squares with non foil covered insulation and used a large aerial that was enough to get a decent signal, however we aren't very far from quite a strong transmitter. Try entering your postcode here.. http://www.digitaluk.co.uk/reception_guide or send us your postcode by PM and we might be able to recommend an aerial. The usual rules for good reception are: Use right type and size of aerial. Mount it as high as possible. Use good quality down lead. Avoid "back of the set" booster amplifiers. Better to use a bigger aerial, if you really must use an amplifier it should be fitted on the mast near the aerial. If you want Freeview in several rooms consider putting a powered "Distribution amplifier" (aka "Loft Box") in the loft. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 27, 2017 Share Posted October 27, 2017 13 minutes ago, Moira Niedzwiecka said: Jeremy, thank you for your reply. We are going to have to work out how to get the in roof PV cables and the cables for the alarm & external lighting through as well. We also have to vent the soil stack to the outside too as we are the only ones on this sewer run. We didn't really want an external SVP so will have to go out through the gable end wall. Instead of wasting heat and creating a thermal bridge through the wall for the SVP, have you looked at an external low level vent, in a discreet place in the garden? These can work well, and rarely give off any odour, especially if located close to plants. Low level vents are quite commonplace in sewer systems, especially in older urban areas. They are also very commonly used on septic tanks and treatment plants, too. If it were me then I would try and remove the need for such a relatively significant thermal bridge as this, not just because of the small additional heat loss, but because it may well be a condensation risk. The air flowing up that pipe will be cool, probably around 8 to 10 deg C, so will be below the dew point of the water vapour in the air in the house, and the chimney effect of vent air flowing up that pipe may tend to cool down the whole foul drain network of piping inside the house, too, creating cold spots. Normally the soil pipes inside the house (with no vent) will fairly quickly warm back up to room temperature after flushing, but not if there is a flow of cool air going through them from outside. Link to comment Share on other sites More sharing options...
Moira Niedzwiecka Posted October 27, 2017 Author Share Posted October 27, 2017 I am worried about the very issues you have highlighted. We asked building control if we could duct out through foundation & locate stack on the side of the garage. They said too far away. I thought that the vent to air had to be above the level of the highest loo. We have a garden area to the side of the house that will be planted up & would happily site the vent there if it could be low level. It would be about 3m from the house. Link to comment Share on other sites More sharing options...
ProDave Posted October 27, 2017 Share Posted October 27, 2017 3 minutes ago, Moira Niedzwiecka said: I am worried about the very issues you have highlighted. We asked building control if we could duct out through foundation & locate stack on the side of the garage. They said too far away. I thought that the vent to air had to be above the level of the highest loo. We have a garden area to the side of the house that will be planted up & would happily site the vent there if it could be low level. It would be about 3m from the house. My BC insisted on a vent through the roof unfortunately. I had hoped the vent at the end of the run at the static caravan would have been sufficient but he took the view that might one day be removed and the vent capped. He would have accepted an external vent up the gable end of the house, but unfortunately by the time I knew this, I had already concreted the parking area so it was too late to do that. But if you are still able, you should be able to connect into the pipe run and put a vent up the gable wall of the house. Link to comment Share on other sites More sharing options...
Moira Niedzwiecka Posted October 27, 2017 Author Share Posted October 27, 2017 Thanks Dave. Another problem is that we have quite a few opening roof windows & it is difficult to position the vent the correct distance from any one of these. What a pain. I had hoped all these details would have been considered by the architect but it seems not. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 27, 2017 Share Posted October 27, 2017 The problem is one of overcoming engrained habits, rather than looking logically at what the vents actually do. The vent or AAV at the highest point is to prevent there being a partial vacuum in the vertical soil pipe drop when a toilet is flushed, that's all, nothing more. The vent at the end of the foul drain is there to prevent a pressure build up and ensure that the foul drain is at normal atmospheric pressure. The regs actually do make this clear, but the approved document doesn't, really. This means you can comply with the regs by having a low level vent some way from the house, at the end of the foul drain, ideally in a hedge or flower bed, plus an internal AAV above the height of the highest pipe feeding to the soil pipe. Both have different functions, and you may need to tactfully explain to the building inspector how you are complying with the regulations by having these two separate vent systems, that each address a specific, but different, vent requirement Link to comment Share on other sites More sharing options...
Moira Niedzwiecka Posted October 27, 2017 Author Share Posted October 27, 2017 Jeremy, thank you. The drainage has been a problem from the start. We were going to have a mini waste treatment plant to start with. The percolation test was ok for foul & surface soakaway. After a very wet winter both we & BC were not convinced it was the right thing. We managed to get an easement from the farmer to duct through his field & woodland to the main combined sewer for the village. It was 110m away & we hit rock halfway. We are elevated so had to go really deep to start with to get the correct gradient so we did not come out of the ground before we reached the main sewer. You would have thought we were building crossrail! Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 27, 2017 Share Posted October 27, 2017 (edited) It looks to me as if you may well have scope for a low level vent, higher than the top of the foul drain run (shall we call it mini-Crossrail? ) perhaps suitably hidden somewhere, to deal with the pressure equalisation issue in the long foul drain run. You can then fit an AAV high up in the house to deal with the separate issue of the possible partial vacuum caused when an upstairs toilet is flushed. I had to make the case to do something very similar to the BCO, rather than my building inspector, as I knew that it was a bit out of the ordinary. In our case we have a treatment plant, that incorporates a low level vent (just a few hundred mm above ground level) that performs the requirement of equalising the pressure in the foul drain. I did not want to fit an SVP through the roof or out through a wall, so I wrote a carefully worded request directly to the BCO, with drawings, explaining how I proposed to deal with the two different vent requirements in the regulations. I also explained why I needed to avoid running an SVP through the wall or roof, and the consequences that doing so may have on the thermal performance of the house. He accepted this without question, and agreed that, although this was not a standard means of addressing the requirements, as suggested in the guidance in the approved document, it was OK and did comply with the building regulations themselves. It's important to note that the approved documents (in this case Part H) are not regulations, they are just methods and guidance that MAY be used to comply with the building regulations, but equally they are not the only way that the regulations can be complied with. Edited October 27, 2017 by JSHarris Link to comment Share on other sites More sharing options...
Onoff Posted October 27, 2017 Share Posted October 27, 2017 Silly question but do you know what transmitter you want to pick up from? It'll be the one the majority of the local aerials are pointing at. ...and do any of your gables point that way, or near enough. Cunning plan...maybe. Link to comment Share on other sites More sharing options...
Moira Niedzwiecka Posted October 27, 2017 Author Share Posted October 27, 2017 (edited) Our location is approx 6 miles from the Waltham transmitter. It was an analogue TV mast. I am sure if the same mast is now digital. It is north of us and the front elevation of our house points directly at it.The gable ends are east/west. There is nothing between us and the mast , it is clearly visible. I love seeing the red mast lights at night across the valley. Edited October 28, 2017 by Moira Niedzwiecka Link to comment Share on other sites More sharing options...
Moira Niedzwiecka Posted October 27, 2017 Author Share Posted October 27, 2017 Jeremy, I know this is a big ask, but could you let me have a copy of the relevant parts of your letter to Building control? The head of Building Control who I am dealing with is really helpful & very interested in our project as it is new to him as well. I have explained the problem we have in ducting to the outside and the negative effect it would have. He is trying to help and open to suggestions. My problem is I don't understand enough to make any new suggestions. Link to comment Share on other sites More sharing options...
Gone West Posted October 28, 2017 Share Posted October 28, 2017 I have a low level, around 500mm high, vent two metres from my sewage treatment plant and around seven metres from my house located in the flower bed. I have AAVs in the house and all of this was accepted by the BCO without question. Link to comment Share on other sites More sharing options...
Moira Niedzwiecka Posted October 28, 2017 Author Share Posted October 28, 2017 Thank you Peter, I am going to speak to building control next week. We need to finalise how we are doing this before the roof & render go on. I am going to get the firm of structural engineers & designers that did out foundation & drainage plans to try & sort it out. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 28, 2017 Share Posted October 28, 2017 (edited) 22 hours ago, Moira Niedzwiecka said: Jeremy, I know this is a big ask, but could you let me have a copy of the relevant parts of your letter to Building control? The head of Building Control who I am dealing with is really helpful & very interested in our project as it is new to him as well. I have explained the problem we have in ducting to the outside and the negative effect it would have. He is trying to help and open to suggestions. My problem is I don't understand enough to make any new suggestions. @Moira Niedzwiecka, I've just dug out the old email I sent to the BCO, this is the text of it: Quote I have a query regarding the soil pipe stack ventilation system that I would like to use and would value your opinion, please. As I understand Part H, an AAV is acceptable as an alternative to an external vent pipe provided that the remainder of the foul drain is ventilated. In our case the foul drain runs to a ventilated treatment plant (which has a vent on the top) and there is no interceptor trap between the soil pipe stack and the treatment plant, just a single 450mm inspection chamber. My understanding of Part H, particularly paragraphs 1.33 and 2.18 leads me to believe that this arrangement should be compliant, but I may well have misinterpreted some subtle detail. I have attached a sketch showing our proposed layout, together with the site plan showing the foul drain layout that you already should have. We have a single vertical soil pipe stack just inside the north wall that is close to the upstairs and downstairs toilets and wash basin and bath/shower drain points. The kitchen sink and dishwasher etc drains to a separate external gulley, with a trap, at the front of the house, adjacent to the inspection chamber, via a 1.5” waste pipe through the front wall. Because of the heat loss associated with a large diameter externally vented soil pipe stack (in effect this would form a cold chimney running up inside the heated envelope of the house) and because this is a passive house, where I wish to minimise the number of penetrations through the air tightness layer and minimise heat loss, I would prefer to use an AAV fitted high up in the eaves service area than an external vent through the roof. This eaves services area is of a high volume (around 15m³) and is ventilated to the rest of the house via the normal gaps around the access door to it (this area also houses our DHW cylinder and MVHR unit and ducting). I would be grateful for your opinion on this, as we are about to fit the roof covering. I included these two drawings: Elevation - Section showing foul drain stack - A4.pdf Floor Plan - Services - A4.pdf This was the reply I had back from the BCO (actually his full title was Building Control Area Manager): Quote Hello Jeremy – sorry for not getting back to you sooner. Your interpretation of the Regs. for vent pipes is correct. I can’t see any reason why you cannot use an air admittance valve as you suggest. However you should make provision for easy access to the valve for maintenance purposes. I hope this, together with @PeterStarck similar arrangement, helps. In essence there is no practical difference between the requirements for ventilating the foul drain leading to a treatment plant and those for a foul drain connecting to a main sewer. The issue here is that building inspectors are far more familiar with the combined SVP arrangement, where a single vent pipe has two puposes, one to prevent the creation of a partial vacuum in the vertical soil pipe when a toilet flushes and the second to equalise the pressure in the foul drain and connected sewer/treatment plant to the atmosphere so that there can be no pressure build up. The single SVP solution is cheap and easy, so is very commonly used, especially on mass produced houses, but having two separate methods for dealing with each of the ventilation requirements is perfectly acceptable within the regs. Edited October 28, 2017 by JSHarris Link to comment Share on other sites More sharing options...
Temp Posted October 28, 2017 Share Posted October 28, 2017 (edited) 15 hours ago, Moira Niedzwiecka said: Our location is approx 6 miles from the Waltham transmitter. It was an analogue TV mast. I am sure if the same mast is now digital. It is north of us and the front elevation of our house points directly at it.The gable ends are east/west. There is nothing between us and the mast , it is clearly visible. I love seeing the red mast lights at night across the valley. Details of the Waltham here.. https://ukfree.tv/transmitters/tv/Waltham All digital now. I think all the analogue TV transmitters in the UK have been switched off now. If you scroll down to "How will the Waltham (Leicestershire, England) transmission frequencies change over time?" there is a table showing the aerial band needed. In general an aerial designed for just one part of the band (eg Band A) is better than a wideband (Band W) aerial as they "let in" less noise. The table says that at the moment you need a wideband aerial (Band W), however around 31st March 2018 the frequencies will change so you will be told to retune your TV. After that you only need a band A aerial but a band W would continue to work. Over time parts of the TV band will be sold off to the mobile phone networks. It's possible that when this happens (>2020?) people with a wide band aerial will see some interference/blocking or other issues. At that point the cure might involve replacing a wideband/band W aerial with a narrow band aerial (in your case a band A) or possibly the addition of a filter. In short. if you are putting up an aerial now and want good TV for Christmas I'd go for a wide band aerial in the loft. If it won't get done until after 31st March I'd probably put up a Band A aerial on the chimney (if you have one) or gable end?. Many places only sell band W aerials because it means they don't have to stock so many models of the same aerial. Sometimes the colour of the plastic bung on the end of the aerial indicates the band. eg Black for wideband/band W and red for band A. Bit more later as I have to take my kids out. I need to check which direction the transmitter is from you because it doesn't broadcast equally in all directions. Just for info, this is the typical frequency response/bands for TV aerials. You can see that band A aerials don't allow signals from the top end of the band (right hand side) where mobile phones are going to appear. Edited October 28, 2017 by Temp Link to comment Share on other sites More sharing options...
Moira Niedzwiecka Posted October 28, 2017 Author Share Posted October 28, 2017 Gosh Temp, That is some information. I had no idea. Thank you. We do not have a chimney. We really wanted to have an interior aerial in the roof space so as not to break the thermal envelope of the house. Do you think this is possible with the 'loft box' amplifier you mentioned before? Our roof build up is natural slate on 25mm horizontal battens, sarking membrane, 25mm vertical battens, Solitex membrane, OSB, 300mm warmcell blown cellulose insulation, Smartply vapour control board. We will definitely not be in by March next year. I wish. Regards Moira Link to comment Share on other sites More sharing options...
Temp Posted October 28, 2017 Share Posted October 28, 2017 (edited) A loft box is just for splitting and distributing the signal to multiple TVs, they don't really amplify the signal much. The problem with amplifiers is they also amplify noise and unwanted signals and add some noise of there own making. It's almost always better to use a bigger aerial rather than a small aerial and an amplifier. I've had a look at what's on the roofs in surrounding villages using Google streetview and they seem to me using medium or large aerials. So I think I'd start with something like one of these in your loft.. Wideband http://aerialsandtv.com/atvschoiceofaerials.html#Log36 Band A http://aerialsandtv.com/atvschoiceofaerials.html#Yagi18 (Specify band when ordering) If it won't go in before March I would wait until then before buying one. See if the retune happens and then perhaps go for the Band A. The wideband will work after the retune but you might have interference from mobile phone at some point. The band A won't receive all channels until the retune but should be more immune to mobile phones when they are introduced. I don't know which way your house is orientated but if you have a gable end pointing towards the transmitter I would run good quality aerial lead to the ridge at that point as well as the loft just in case an indoor aerial doesn't work well. You can get cranked poles and brackets for mounting aerials to or above a gable end. Good cable should be double screened (has both a foil and a braid screen). http://aerialsandtv.com/onlinecableandmisc.html#Cable You want enough to have several meters spare at each end. For example so there is enough to run up a short pole and possibly to the pointy end of the aerial. Well worth putting a power point in the loft (and possibly a light as well). PS: I've no connection with any of the companies/links above. They are just a good source of reference material. Plenty of other suppliers around. Sometimes a local installer is better than a national company as they have more relevant local experience. There are plenty of cowboy aerial installers out there as well. Edited October 28, 2017 by Temp Link to comment Share on other sites More sharing options...
Moira Niedzwiecka Posted October 28, 2017 Author Share Posted October 28, 2017 Thank you Temp, this is so helpful. Just one last question. This may be silly but does the TV aerial have to be mounted on the house? Does the length of the cable have any bearing on the signal reception? If not & the internal aerial does not work could we mount an aerial on the garage? We are in open countryside and in an elevated position. If this is a possibility we could put an aerial cable through some existing service ducting that is entering the house through the foundation and coming up through the insulated floor. We have yet to lay the 200mm of floor insulation which will have a 6mm self levelling top screed. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 28, 2017 Share Posted October 28, 2017 (edited) Is there any reason why, if you can't get a signal with an internal aerial, that you can't just run the cable through the wall and fit an external aerial? We have a similar wall build up, 300mm of cellulose with board skins either side, and although it took an hour or so of work to get a bit of plastic conduit through the wall and then feed a load of cables through it (we opted for a Freesat dish on the back of the house, which has four cables) there was no real problem in doing this, it was just a bit fiddly to do. The airtightness of the house isn't impacted, as the cables are easily sealed at either end in the conduit, and the thermal bridge in negligible. Also, having a bit of conduit running through the wall makes replacing cables in future pretty easy. Edited October 28, 2017 by JSHarris Link to comment Share on other sites More sharing options...
ProDave Posted October 28, 2017 Share Posted October 28, 2017 Our tv aerial is on the shed, about 10 metres or more from the house. We have a masthead amplifier there mainly to overcome the loss in the cable from there into the house, where it then feeds the distribution amplifier. Link to comment Share on other sites More sharing options...
Onoff Posted October 28, 2017 Share Posted October 28, 2017 (edited) I built a couple of horizontally polarized, trough antennae for friends locally. Designed for optimum performance 538MHz i.e dead centre of Band A. They work a treat. A trough antennae is really just a corner reflector with the vertex removed and replaced with a plane reflector - which lends itself to fitting against a wall...or gable. These are vertically polarized, imagine turned thru 90deg for horizontaliy polarized. Waltham's signal is horizontally polarized. So a corner reflector: And a trough antennae, as above but with the vertex taken off: The construction can be sheet ali or mesh. For the first I used sheet ali. The second one was done in 1/2" galv mesh. If mesh is used it needs to be ideally 1/12 wavelength or smaller. I made the dipoles from 8mm ali tube from memory. I reckon the plane reflector could be hidden by the cladding on a gable then just have the two wings in mesh and the dipole on show. Admittedly probably not the off the shelf solution the OP was after! I'll maybe redo the maths later as I've mislaid my original paper calcs. They're don't come out small btw. +1 on www.aerialsandtv.com , great company. Scroll down to the table above the picture and see their recommendation for an aerial: http://www.aerialsandtv.com/walthamtx.html Tbh they're really nice people to talk too. Give them a ring. Edited October 28, 2017 by Onoff Link to comment Share on other sites More sharing options...
Moira Niedzwiecka Posted October 30, 2017 Author Share Posted October 30, 2017 Jeremy, I just wanted to say how much I appreciate the information with regard to the SVP & building control. I have spoken to head of building control this morning & he is going to look into further for us. I will let you know what happens. Thank you. Moira Link to comment Share on other sites More sharing options...
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