Attic insulation-3bed semi

elchanco

Hi,

I want to re-insulate my attic this winter. I currently have Rockwool Blown Loft Insulation for the last 5years.
I’m considering insulating over this with new insulation, preferably the type that I can roll between the joists. Is this advisable or should I go to the hassle of removing the old insulation beforehand (id rather just insulate over it).

Also, any recommendations on which type of insulation to use?

I have some condensation on the north facing felt during severe cold snaps. I’m hoping that proper insulation will prevent this occurring.

Any suggestions much welcomed.

RKQ

elchanco wrote: »

I want to re-insulate my attic this winter. I currently have Rockwool Blown Loft Insulation for the last 5years.
I’m considering insulating over this with new insulation, preferably the type that I can roll between the joists. Is this advisable or should I go to the hassle of removing the old insulation beforehand (id rather just insulate over it).

It depends on the thickness of the existing insulation - has it sagged? If not then it should be fine, so you can add insulation over it perpendicular to the joists. Try to achieve 300mm thickness overall ( including existing insulation).

elchanco wrote: »

Also, any recommendations on which type of insulation to use?

Rockwool or fibre glass will be fine. Check U-value rating to compare like for like. Usually good deals on insulation at this time of year so shop around.

elchanco wrote: »

I have some condensation on the north facing felt during severe cold snaps. I’m hoping that proper insulation will prevent this occurring.

Ventilation will prevent condensation. Unfortunately during the very cold spell last year, there was very little wind, therefore there was little air movement. Increasing insulation will help to a point but increased ventilation is required to cure condensation. Install vent slates, ridge vents or a wall vent in both gables can help sometimes.

elchanco

Cheers RKQ for the reply.

The current insulation i have is just very uneven around the attic. So you would advise laying the insulation perpendicular to the joists. The joist would be totally covered, is this normal practice!

I put two vent tiles in the north face side of the roof, around midway. This resulted in no difference in condensation. I know, we had a very cold winter last year so that didn’t help.

Hopefully I can adequately insulate the attic & solve the condensation problem this winter
:rolleyes:

elchanco

Im going to re-insulate the attic this week. Any tips on laying the insulation and any other helpfull advice?

cheers

slimjimmc

elchanco wrote: »

Im going to re-insulate the attic this week. Any tips on laying the insulation and any other helpfull advice?

cheers

Wear a dust mask, goggles and gloves. Loose fitting light clothes make moving around much easier. Don't worry about feeling cold, you'll be roasting after a few mins. A few rubber bands or tape over the cuffs helps prevent itchy wrists.

Get enough light up there too, it gets risky when you can't see what you're stepping or kneeling on.

Use a couple of wide boards or similar for walking and kneeling on, you'll need enough boards that you can shift around while on your knees.

Unopened rolls are much easier to handle so move them into position where you want to lay them. Try to align the end of the insulation up against the wall so that when you open the roll it just unravels neatly across the ceiling without you needing to do a lot of dragging or pulling to get it into place.

Work from the eaves back towards the centre, laying the rolls across the joists. You may need to push the insulation outwards towards the eaves but don't push it too tight into the corner. Make sure you leave a good 50-100mm gap between the rafters to allow ventilation from the eaves.

All electrical cables supplying heavy duty appliances (showers, cooker, immersions, etc) should be left on top of any insulation to avoid any risk of them overheating.

If you need to cut a roll because it's too wide (eg, the last row), use a handsaw and cut it before you open the roll, much easier.

Have a few beers chilling in the fridge for when you finish.

elchanco

Cheers slimjimmic,
That’s exactly the type of info I need. The only part im looking forward to is the "beers chilling in the fridge"...

I currently have blown insulation in the attic, when you say "lay the rolls across the joists".. I was going to lay the rolls between the joists, would this not be advisable!

The condensation is back because of the chilly weather, is it advisable to insulate while this exists?

Cheers again for the help!

My wife wants to pay a "pro" to do it but I believe the job is very do-able.... or is it?

nophd08

elchanco wrote: »

Cheers slimjimmic,
That’s exactly the type of info I need. The only part im looking forward to is the "beers chilling in the fridge"...

I currently have blown insulation in the attic, when you say "lay the rolls across the joists".. I was going to lay the rolls between the joists, would this not be advisable!

The condensation is back because of the chilly weather, is it advisable to insulate while this exists?

Cheers again for the help!

My wife wants to pay a "pro" to do it but I believe the job is very do-able.... or is it?

I would lay it across the joists, dont worry about condensation, extra insulation should help.
No harm in wearing knee pads. Can be bought cheap enough in hardware store. Your knees will thank you for it.
Job is very do-able for the DIY'r. You'll be well pleased when its finished.

elchanco

Any recommendations on which insulation to buy. I’m going to go to B&Q tomorrow because we have a 200e voucher for that store.

paddy147

elchanco wrote: »

Any recommendations on which insulation to buy. I’m going to go to B&Q tomorrow because we have a 200e voucher for that store.

Knauf 170mm attic insulation in Homebase.

Now reduced from 49 euro to only 13 euro.YES 13 euro a roll.:D

trotter_inc

I'm doing something similar next weekend, I'm adding extra insulation in to our attic which is currently covered with the "shredded type" of insulation. In the corners of the attic where the roof meets the attic there are ventilation grids which are letting in a huge amount of cold air and resulting in drafts. Is it Ok to cover over some (or all) of these ventilation grids for the winter months?

MicktheMan

trotter_inc wrote: »

I'm doing something similar next weekend, I'm adding extra insulation in to our attic which is currently covered with the "shredded type" of insulation. In the corners of the attic where the roof meets the attic there are ventilation grids which are letting in a huge amount of cold air and resulting in drafts. Is it Ok to cover over some (or all) of these ventilation grids for the winter months?

No. It is vital that these vents stay unblocked. Close/seal gaps / cracks from the attic to the house to reduce draughts.

RebelButtMunch

slimjimmc wrote: »

Try to align the end of the insulation up against the wall so that when you open the roll it just unravels neatly across the ceiling without you needing to do a lot of dragging or pulling to get it into place.

Work from the eaves back towards the centre, laying the rolls across the joists.

Hoha I love this idea. I was thinking of sawing the rockwoll to match the gap between the joists. Is it just as good (thermally) to roll it out perpendicular to the joists?

WHU

Great thread hope you don't mind me asking a question here.

Is there any difference, quality wise, between the blown in loose insulation to the traditional rolls. I'm thinking of getting the attic done and the loose has been recomended.

slimjimmc

RebelButtMunch wrote: »

Hoha I love this idea. I was thinking of sawing the rockwoll to match the gap between the joists. Is it just as good (thermally) to roll it out perpendicular to the joists?

Thermally speaking, if you're only going to put down one layer, I think laying across the joists can be better than laying along them simply because it should help insulate the joists too and reduce thermal bridging. However, why waste all that space between the joists when you can put it to good use by filling it with another layer of heat-saving insulation? I'm only a DIYer so this is only an opinion.

WHU wrote: »

Great thread hope you don't mind me asking a question here.

Is there any difference, quality wise, between the blown in loose insulation to the traditional rolls. I'm thinking of getting the attic done and the loose has been recomended.

It depends on the U-value of the insulating material. Various materials (e.g. bead, cellulose) can be used for loose insulation and various other materials can be used for rolls (fibreglass, rockwool, sheep's wool).
You need to compare the U-value and pick the material with lowest U-value you can afford. There are other factors to consider, such as installation costs and how it performs over time.

MicktheMan

slimjimmc wrote: »

Thermally speaking, if you're only going to put down one layer, I think laying across the joists can be better than laying along them simply because it should help insulate the joists too and reduce thermal bridging. However, why waste all that space between the joists when you can put it to good use by filling it with another layer of heat-saving insulation? I'm only a DIYer so this is only an opinion.

Don't leave any gaps under the insulation layer as there will be air movement under the insulation and this will negate the insulation (in fact, you will actually be insulating nothing!). First lay between the joists to the same depth of the joists and then if a second layer (which I would strongly recommend) is being layed, run this perpendicular to the joists. The current standard is 300mm so thats 3 x 100mm or 2 x 150mm depending on joist depth.

trotter_inc

WHU wrote: »

Is there any difference, quality wise, between the blown in loose insulation to the traditional rolls. I'm thinking of getting the attic done and the loose has been recomended.

I just spent last night and this morning re-insulating my attic. When we bought the house the attic had that loose insulation in it, after closer inspection last night I realised that the builders did a terrible job of spreading it. Some sections of the attic barely had any coverage. I spent 3 hours on my knees patting all the loose insulation in between the joists to see exactly how much insulation was actually up there. After seeing how bad it was I went to the Co-op store this morning and bought 6 rolls of the "rolled up" insulation and recovered the whole attic space (we've a 3 bed semi), turned out pretty well and was really easy to fit.

In my opinion, I would go with the rolled stuff before the loose stuff as you know exactly how well the attic is insulated.

Cost wise, the 6 rolls (6 inch) cost me €95 in Dairygold Co-op.

Good luck with it

MicktheMan

trotter_inc wrote: »

I just spent last night and this morning re-insulating my attic.

Good job.
Hope you left those vents free to ventilate the attic:)

elchanco

I’m happy I started this thread, some great feedback.

I spent a lot of time filling in between the rafters with the blown insulation that was supplied by the builder. I can’t understand why people would choose this type of insulation, its crap! It was very uneven around the attic.

I cleared the blown insulation from under the water tank (top avoid it freezing). Do i roll the insulation as far as the tank, cut it, and then roll across the other side of the attic. Or is there a better way of keeping the tank clear?


CHEERS AGAIN FOR ALL THE VALUABLE FEEDBACK.

iMax

Did my attic in January this year (after threatening to for seven years). We had that blown stuff & I spent the first day scooping up s much as I could & using it for the parts where the joists were not the full width.

Then got 200mm B&Q own brand & put that between all the other joists. We need the storage space up there so laying a perpendicular layer wasn't an option. Instead I floored the attic.

All the pipes were wrapped with foam for as far as I could get them (some very tight space squeezing went on). I also bought three rolls of the kneff "space" insulation & some duct tape & wrapped the whole water tank up there (leaving the space underneath it which is above the hot press empty), so that's a huge silver bubble up there.

Next step was to get some polystyrene for the trap & I also got some sticky foam for around it.

Lastly I got the rest of the pipes in the hotpress wrapped in foam too & got another lagging jacket on the emersion.

Total cost was approx €475 & the whole project took me about a week - although there was a lot of stuff to move around up there & & also a lot of woodwork with the floor.

The result is that our gas boiler which was running at 5 in the last cold snap is now running at 2 & for about 30 mins less per day. The house isn't "Toasty" warm as I'd like it, but it's not cold either.

Horrible job putting it in though.

MicktheMan

elchanco wrote: »

Do i roll the insulation as far as the tank, cut it, and then roll across the other side of the attic. Or is there a better way of keeping the tank clear?
.

You could do that but you can also do the following:
Cut a light piece of ply roughly the shape of the top of the tank and place it over the tank. Roll the insulation up the side, over the top and down the other side and then continue with the attic. If you are laying a second layer of insulation perpendicular to the first (recommended), do the same when you get to the tank. Use light string to tie the insulation around the bottom and top of the tank to keep it in place. Do not make it tight, just enough to keep it in place. Fill in any gap in the insulation around the tank (basically, you should not be able to see any of the bare ceiling underneath the tank). And remember to make sure that all pipes are well insulated.
Btw, this assumes you have a rectangular shaped tank. If circular then it's a bit trickier;)

slimjimmc

MicktheMan wrote: »

You could do that but you can also do the following:
Cut a light piece of ply roughly the shape of the top of the tank and place it over the tank. Roll the insulation up the side, over the top and down the other side and then continue with the attic. If you are laying a second layer of insulation perpendicular to the first (recommended), do the same when you get to the tank. Use light string to tie the insulation around the bottom and top of the tank to keep it in place. Do not make it tight, just enough to keep it in place. Fill in any gap in the insulation around the tank (basically, you should not be able to see any of the bare ceiling underneath the tank). And remember to make sure that all pipes are well insulated.
Btw, this assumes you have a rectangular shaped tank. If circular then it's a bit trickier;)

You could wrap some of the roll around the 4 sides of the tank and tie it in place with some string. Keep the insulation flush with the top of the tank and fill any gaps at the base. Then use a lid like MicktheMan suggests and drape some short lengths of insulation across the top.

The short lengths would be much easier to remove and, more importantly, easier to replace properly every time you need access to the tank, whilst providing the same protection as a continuous roll.

elchanco

Forgot to ask about proper insulating over the loft ladder I had a loft ladder installed during the summer...:rolleyes:

iMax

elchanco wrote: »

Forgot to ask about proper insulating over the loft ladder I had a loft ladder installed during the summer...:rolleyes:

You could close the hatch with you in the attic, line it with some polythene (including around the ladder rungs etc), then spray in a small amount of expanding foam.

If you do it right, when it's cured, you'll be left with a fairly decent insulation pad.

dathi

the handy way of insulating your water tank is to use kingspan and cut the sheets to the size of tank you can use duck tape to hold it around the tank and use a sheet for the lid no mess if you need to get at your tank for maintance . some people make an up stand of kingspan around the loft opening. you make it a small bit taller than the top of the ladder when the hatch is closed. you also make a lid for it then when you are coming down from the loft you put the lid on the up stand step down your ladder and close the ladder hatch job done

positron

OP, if you don't mind me asking something here..

Thanks to a bargain alert here, I got 4 rolls of 170mm glass fiber insulation from HomeBase (13.99 each). House is 15 years old, and there's about 150-180mm insulation in place between the joists, and I spread two of the rolls on one side of the attic across the joists - it dead easy, took me less than 30 mins. Now thinking of doing the other half of the attic now, but I can see there's a few cables running across over the existing insulation. There are no downlighters or anything, it's just feeding to normal light in bedrooms below. Question is, would it be okay to roll the new 170mm layer over them? They don't have enough slack to let the roll go under them, so if they can't be under the 170, I will have to patch and lengthen all the cables (more work). Any ideas?

Thanks a mill!

willbur

just thinking , do you wish to use the attic space because having insulation all over the foor means you cant put anything on it and if you do put stuff on the floor you squash the insulation from 300mm down to 100mm , reducing its ability to reduce heat loss ,allso the air in the attic space becomes colder and therefore all pipe work would have to be well insulated ,

maybe think about isulating the rafters , using 80/100mm fire proof polyiso insulating board which can compress between the rafters allowing a 50mm gap between isulation and the roof felt/breathable membrane allso a 25mm/35mm sheet of polyiso can then cover the insulation between rafters and the rafters them selves with alluminium foil taped along the joints and
leaving the attic space available to use:cool:

markit

Hello, sry for butting in, but am wondering if anyone has any advice, we bought a 2nd hand 4 yr old house.
The attic has been converted, but walls are just a single layer of plasterboard with rockwell insulation (the bare minimum) stuffed in behind.

I have re-insulated and topped up between the joists, but what's the best way of insulating behind the palaterboard, especially on the sloping apex?

Also, whats the best way to insulate attic hatch doors and a folding attic door?

Many thanks

elchanco

Hi,

Well, I’ve re-arranged the blown insulation between the rafters & ready to lay the new rolls of insulation. The problem I have at the moment is very bad condensation on the north facing felt. The cold snap that we are experiencing has produced this problem.

My question now is, should I wait until temperatures rise & condensation reduces before I lay the new layer?

Cheers

bobaggio

planning to lay insulation myself this week as we have none as its a 30yo house. Can anyone tell me....does insulation make that much of a difference?
cheers,

iMax

bobaggio wrote: »

Can anyone tell me....does insulation make that much of a difference?

See my post above. Although I did have the heat up to 3 this week for a short time

RebelButtMunch

Slightly off topic but I put 50mm insulated plaster board outward walls in the bedrooms last week and it made a HUGE difference.