Is my new house going to fall down?

pearly20

Hi there,
My other half should be posting this as he has more building terminology but as hes computer phobic I'll give it a try. We have just finished a 2 storey 70sq m extension on the side of a 3 bed semi. Whilst observing a neighbours similar extension being built we noticed that where the roof joins the outer walls the neighbours builder has attached metal strips on the inside, every 1m or so, that seem to strap the roof onto the blockwork. Our builder didnt do this and is away till Feb 1st so we cant ask him about it. Neighbours builder says they MUST be used to secure roof properly...any comments at all? I am hearing that we will need to gouge out the walls, even in the beautifully tiled new bathroom, and insert these metal strips now. Is this correct? Are there any other options? What happens if we do nothing, will the house fall down!!! HELP!!! Thanks

muffler

pearly20 wrote: »

Hi there,
My other half should be posting this as he has more building terminology but as hes computer phobic I'll give it a try. We have just finished a 2 storey 70sq m extension on the side of a 3 bed semi. Whilst observing a neighbours similar extension being built we noticed that where the roof joins the outer walls the neighbours builder has attached metal strips on the inside, every 1m or so, that seem to strap the roof onto the blockwork. Our builder didnt do this and is away till Feb 1st so we cant ask him about it. Neighbours builder says they MUST be used to secure roof properly...any comments at all? I am hearing that we will need to gouge out the walls, even in the beautifully tiled new bathroom, and insert these metal strips now. Is this correct? Are there any other options? What happens if we do nothing, will the house fall down!!! HELP!!! Thanks

I wouldnt worry too much about it. Galvanised mild steel straps are used to anchor the gable walls - basically to stop the gable wall from moving but in fairness this is a practice that only emerged in the last few years. The method of fixing the roof to the rear and back walls and with the barge in place above the gable wall is usually sufficient.

However it is something that your builder should have done. Get him back to correct the issue now and he wont necessarily have to go below the ceiling level with the strapping so your bathroom will be OK. If you had someone supervising the works you should also bring it to their attention.

sydthebeat

pearly20 wrote: »

Hi there,
My other half should be posting this as he has more building terminology but as hes computer phobic I'll give it a try. We have just finished a 2 storey 70sq m extension on the side of a 3 bed semi. Whilst observing a neighbours similar extension being built we noticed that where the roof joins the outer walls the neighbours builder has attached metal strips on the inside, every 1m or so, that seem to strap the roof onto the blockwork. Our builder didnt do this and is away till Feb 1st so we cant ask him about it. Neighbours builder says they MUST be used to secure roof properly...any comments at all? I am hearing that we will need to gouge out the walls, even in the beautifully tiled new bathroom, and insert these metal strips now. Is this correct? Are there any other options? What happens if we do nothing, will the house fall down!!! HELP!!! Thanks

without knowing the indepth information regarding the design, materials and sizes... its very hard to comment on such a matter.
All i would say is that you should have some professional engaged to 'certify' the work... you shouldnt be paying a builder directly if you dont know what is required of him.

AckwelFoley

Muffler, i think she may be referring to wallplate straps

Wallplate straps are the most common method of securing a roof to the blockwork. There is in my opinion too much emphasis placed on this fixing because in my exp the straps are rarely fitted correctly. The roof you might be suprised to know pearly is help on almost entirely under its own weight. Dont worry it wont blow off!

As it is the wallplate (this is the length of timber that runs alond the top of the wall) is secured directly down into the concrete block underneath it with a fixing called express nails. Trust me, these things are very secure, and its likely these are what sere used. I wouldnt panic to be honest. Im rather confident there is not a problem, however as the previous poster said if you have any contacts, get them to look at it..

I can however assure you. The house is not going to fall down. The biggest telltale sign if the roof shifted is there would be a major crack in the ceiling.

Martron

yeah i would kn ow them as wall straps and unless we know the exact method of roof construction it is hard to know if they are fully needed. and as you said before i have rarely seen them installed correctly myself. A good book if you can reference it ( its a bit pricey to buy) is the homebond house building manual. interesting read. breaks down everything with photos and easily followed diagrams.

best thing ( and hardest) is to find a builder..... not a cowboy. If in doubt ask the builder. because you are always better looking at the straps than looking for them!!!!

muffler

Yeah in fairness it could well be the wallplate straps that she is referring to - I didnt take enough time to read the post.

Highly unlikely that the wallplate would not be secured to the wall however its worth investigating.

Martron

muffler wrote: »

Yeah in fairness it could well be the wallplate straps that she is referring to - I didnt take enough time to read the post.

Highly unlikely that the wallplate would not be secured to the wall however its worth investigating.

unlikely but i have seen some crazy things. and also not knowing what ype of roof it is and where it is joinng on to .......

i will give you a good one about extensions..... just before xmas a friend asked me to look at something for him. he is extending the side of his house . long story short the builder had an acrow holding up the new roof . whick was upported off the floorboards of his old kitchen. and this was going to be the final support for the roof. The builder was going to nicely box of the acrow and hide it away from sight. ( how nice of him)

AckwelFoley

No the wallplate would have to be secured to the wall sufficently as to enable to fix the joists and rafters to it. If this is not done correctly, the wallplate would push out as soon as the roof is loaded with tiles, but of course the rood is braced with collar ties to prevent this too.

Look, im not at all worried about this, the weight of the roof alone would be enough to keep to wallplate from shifting. Its difficult for the OP to understand but i have done roofing and i understand the elements involved so all i can say without giving you a boring lecture about the principals of roof design is that im pretty certain your are fine.

250882

Those galvanised straps are necessary. They are something that every architect or engineer will look at when certifying a roof.
Go to the homebond right on site lectures and ask what happens without them. Your builder will have to come back and put them in and I am sure he will have to incur the cost of replacing the tiles in your bathroom. There are strict guidelines on how the straps have to be fixed. You might think I'm being pedantic but assuming that the builder has done something better to fix the roof when he has missed out on these is asking for trouble. If you are really worried call an engineer to take a look.

Martron

snyper wrote: »

No the wallplate would have to be secured to the wall sufficently as to enable to fix the joists and rafters to it. If this is not done correctly, the wallplate would push out as soon as the roof is loaded with tiles, but of course the rood is braced with collar ties to prevent this too.

Look, im not at all worried about this, the weight of the roof alone would be enough to keep to wallplate from shifting. Its difficult for the OP to understand but i have done roofing and i understand the elements involved so all i can say without giving you a boring lecture about the principals of roof design is that im pretty certain your are fine.

my background is civils but try and keep on top of other construction(never know when it comes in handy) Never be afraid to lecture...... human information sponge here!!!!

Mellor

250882 wrote: »

Those galvanised straps are necessary. They are something that every architect or engineer will look at when certifying a roof.
Go to the homebond right on site lectures and ask what happens without them. Your builder will have to come back and put them in and I am sure he will have to incur the cost of replacing the tiles in your bathroom. There are strict guidelines on how the straps have to be fixed. You might think I'm being pedantic but assuming that the builder has done something better to fix the roof when he has missed out on these is asking for trouble. If you are really worried call an engineer to take a look.

We still don't know which kind of straps are refered to.
Wallplate straps aren't always required. Restraint is required but there are different ways to do this;

Straps from the wallplate to blockwork, at 1.8c/c

Straps from the truss directly to the blockwork, at 2m c/c

OR the wallplate can be bolted at 1.2m c/c (must be strapped at butt joints 400c/c max),



If the OP was talking about the barge straps on the gable then these are covered by TGD A, it depends on the height of apex, but generally all will require it. This are at 2m c/c if I remember correct.

pearly20

Hi All,
Thanks for the speedy replies! Obviously I haven't given you all enough information so I will get himself to clarify on this thread when he gets home. Still awaiting final visit from structural engineer (who is taking his time) so I was just hoping to avoid sleepless nights in the meantime...thanks again.

ircoha

Nothing like a bit of strapping to get the circulation going:D.

Just looking at page 153 of the 4th edition of the HBM referred to above and as noted earlier, if fixing the WP it needs to be either strapped down at 1.8m centers or bolted at 1.2m centers and if the WP is butt jointed straps are required at no more than 400 mm each side of butt joint.

So OP it may be possible that the WP is bolted and depending on the length of the walls there may be no butt joints.
[ 70 sqm/2 = 35 => 6 * 6]

Mellor

ircoha wrote: »

Nothing like a bit of strapping to get the circulation going:D.

Just looking at page 153 of the 4th edition of the HBM referred to above and as noted earlier, if fixing the WP it needs to be either strapped down at 1.8m centers or bolted at 1.2m centers and if the WP is butt jointed straps are required at no more than 400 mm each side of butt joint.

So OP it may be possible that the WP is bolted and depending on the length of the walls there may be no butt joints.
[ 70 sqm/2 = 35 => 6 * 6]

Yup, all covered in homebond, I typed my last reply out in a bit of a rush. And mixed up the c/c for bolts and at butt joints.
I edited my last post to included all centrs for three methods, for reference.

Well spotted regarded the length of walls and butt joints ircoha.

AckwelFoley

They are something that every architect or engineer will look at when certifying a roof.
Go to the homebond right on site lectures and ask what happens without them

Dont get me started on them.

Some of them dont know their asshole from their elbow, and i can write a book on some of the screw ups ive seen certified by some these guys.

I can give you the whos who of incompitent engineers, ive used some of them.. :rolleyes:

But of course bands are necessary and important but as i stressed earlier, im on sites every day practically and although fitted and CERTIFIED, they are fitted WRONG! U may as well use ur bootlase to tie down the plate.

sinnerboy

The straps should be put in . The roof wont blow off , but in certain VERY high wind conditions the roof will lift upwards . I would expect that the roof is well fixed to the wall plate and the wall plate is in turn well fixed to the block . So when the roof is lifted up ( Don't be alarmed the affect is momentary and not perceptible when it happens ) ,the roof up lift forces by pass the roof/wallplate fixings and transfer onto the mortar course of the topmost block . This mortar course then shears and causes a crack to appear , the same visual affect as an rc ring beam shrinking - i.e. a continuous horizontal crack about 200 mm down from the ceiling all round .

The problem is not structural insofar as the building will remain stable - but it is a significant cosmetic dis figuration . Get it sorted out . The straps at max 1800 c/c should be min 1000 long so the uplift forces are spread across 4 mortar courses and not just 1 .

You can avoid chopping into the tiles areas if you dont increase the straps spacing by more than 2700 mm at the bathroom but compensate elsewhere if possible . Place a strap to either side of each window , no matter how small the opening . If this affects the bathroom - in that case , so be it . You may get cracked tiles and have to replace anyhow.

OP , I don't expect you to follow this ( I hope that does not sound patronizing - not intended to be ) Print and show this to your builder - engage an engineer if he does not accept this .

AckwelFoley

The up lift you talk is not very common, but does happen. Ive never seen it in my time actually. The time i would be most concerned of somthing happening like this is when the roof is not slated or tiled and the windows are not in. In high wind there can be a risk of shifting if not strapped.

Im not certain, but i remember reading that bolting a wallplate down was not as preferable as strapping, in some cases people rend to over tighten the bolts and this can also cause a problem

But esentially the advice you give is sound advice and should be followed.
If theis builder is certified and insured, i would expect that his engineer would be responsible for covering any issue that could arise.

i hope you hired a reg builder?!

smashey

Meh.

I was in a house today and it will fall down. :eek:

It's only a year old.

My report got shortened to "We would advise that the client engages a structural engineer as a matter of urgency".

AckwelFoley

Oh yea ive seen some real crackers built in my time.


If in Moate sometime, i can show u some real peaches... estates of them infact.

Actually back to my rant on engineers, imy friends bought a house, amd there was a leak in the back of the house down the wall.. i said to to my friends that its the conservetary, the flashing at the roof , the A roof into the main building is probably done wrong.. the water was flowing in practically..

The engineer advised to replace and refit all cills and lintels at the back of house.. i said bollocks, simply the dpc around said items is for DAMP PROOFING houses 20 years ago never even used it an there were rarely problems.

Anyhow after all the replacing and terrible replastering, the leak still persisted, at this point i insisted they tell their own engineer to instruct their engineer that the flashing was done wrong..

et voila.. problem solved.

Professionals :rolleyes:

Im not making any friends with the engineers here with my ranting..but ive had my fair share :P

2 stroke

First roof I ever worked on, before strapping, the guy I was working for insisted on doing a good job of bolting down the wall plate. He retired after that house and I havn't seen a roof as secured since. He believed that the roof "tied the walls together" not that the walls stopped the roof from spreading.

AckwelFoley

If you took the roof off the walls and placed it on the ground.. youd be able to put a herd of elephants on the rige if the roof if constructed properly.. triangulation is the reason for this, you see this easily with trusses.

Its not "holding" the walls togeather, simply because the strength in walls comes from the principles of concrete which is in compression not tension... for example the interior walls are freestanding only on four inches, its the "weight" downwards that keep it upright along with of course them interlocking with the exterior and other interwalls, and the roof is not in anyway fixed to internal walls, the joisting just rest on them.

Look at a chimney again as an example. where a chimney protrudes out from the roof, there is a layer of dpc placed all around the stack and the rest of the stach is built on that.. so there isnt actually a mortar bond at that point and you have perhaps up to 12 foot of a stack sitting there, so if you could imagine a a huge giant hand / crane lifting up the chimney stack, it would be rather easy, simply because there is in effect no bond.. but its the sheer weight of the stack alone that keeps the chimney in place.. esentially the same with the walls.

While spreading is a serious consideration on roof construction, its spreading of the wallplate that a factor, not the walls.. the experior walls are tied together. The roof could spread if it was loaded with tiles and the bracing of the roof not completed.

A roof is designed in such a way that the downward pressure is distributed downwards on the exterior walls, and not at an angle, which would happen if the roof was not braced,

gsxr1

2 stroke wrote: »

First roof I ever worked on, before strapping, the guy I was working for insisted on doing a good job of bolting down the wall plate. He retired after that house and I havn't seen a roof as secured since. He believed that the roof "tied the walls together" not that the walls stopped the roof from spreading.

same here. the lad I served my time with away used 8" rawbolts to fix the wall plate.

any builder I have been with since has been happy to use 75mm steel nails and 3" wire nails with straps every 2 meters to secure the wall plate

sinnerboy

gsxr1 wrote: »

same here. the lad I served my time with away used 8" rawbolts to fix the wall plate.

any builder I have been with since has been happy to use 75mm steel nails and 3" wire nails with straps every 2 meters to secure the wall plate

There is a paradox here . Traditionally wallplates were simply mortar bedded . Gravity , together with plan geometry indeed keeps the roof in place . wind uplift forces did shear the wallplate / mortar bond ( if such a thing really exists ) but to no perceptible consequance .

Now , with the contemporary practice of very good mechanical fixing of the wallplates , wind uplift forces stress the the mortar course of the the topmost blocks , if the wall plate is not strapped

again , the OP must get the builder to sort this

ircoha

snyper wrote: »

If you took the roof off the walls and placed it on the ground.. youd be able to put a herd of elephants on the rige if the roof if constructed properly.. triangulation is the reason for this, you see this easily with trusses.

Its not "holding" the walls togeather, simply because the strength in walls comes from the principles of concrete which is in compression not tension... for example the interior walls are freestanding only on four inches, its the "weight" downwards that keep it upright along with of course them interlocking with the exterior and other interwalls, and the roof is not in anyway fixed to internal walls, the joisting just rest on them.

Look at a chimney again as an example. where a chimney protrudes out from the roof, there is a layer of dpc placed all around the stack and the rest of the stach is built on that.. so there isnt actually a mortar bond at that point and you have perhaps up to 12 foot of a stack sitting there, so if you could imagine a a huge giant hand / crane lifting up the chimney stack, it would be rather easy, simply because there is in effect no bond.. but its the sheer weight of the stack alone that keeps the chimney in place.. esentially the same with the walls.

While spreading is a serious consideration on roof construction, its spreading of the wallplate that a factor, not the walls.. the experior walls are tied together. The roof could spread if it was loaded with tiles and the bracing of the roof not completed.

A roof is designed in such a way that the downward pressure is distributed downwards on the exterior walls, and not at an angle, which would happen if the roof was not braced,

For completeness, while on the topic of 'spreading',
page 159 of the HBM refers to the requirements in TGD A for straps at ceiling height and above with the express intention of helping to stabilize the gable walls, so it is not entirely correct to say that the walls are not supported by the roof.

When in doubt the construction detail I prefer is to fit a reinforced concrete ring beam, using the full lintel block from
http://www.roadstone.ie/Products/Blocks/Standard.htm
around the top of the block work and then fix the WP to it.
This allows for a full or semi-couple roof: see Barrys Building Construction page 256 of the 2005 edition.

AckwelFoley

For completeness, while on the topic of 'spreading',
page 159 of the HBM refers to the requirements in TGD A for straps at ceiling height and above with the express intention of helping to stabilize the gable walls, so it is not entirely correct to say that the walls are not supported by the roof.

Yes, you are correct, i was referring primarley to a hip roof, but yes a high gabe is as you point out in part supported by the straps you refer to.

muffler

Stop confusing the poor lady guys.

@ the OP > Look, I dont think the house will fall in the near future (just a guess now:)) but do get both your engineer and builder back to look at your concerns.

AckwelFoley

Just clarification of some ambigiouty in some earlier replies.

muffler

snyper wrote: »

Just clarification of some ambigiouty in some earlier replies.

Fuck.




Only mods can say that

AckwelFoley

lol...

smashey

muffler wrote: »

Fuck.




Only mods can say that

I can't.

Mellor

****, Can I?



Edit: nope.

muffler

My God - I have to teach you people everything

Have a go here - Its all explained

2 stroke

The poor girls house is falling down around her ears and all you lot can do is talk ****. Get back on topic.

Mellor

2 stroke wrote: »

The poor girls house is falling down around her ears and all you lot can do is talk ****. Get back on topic.

Stop scaremoungering. The topic has been well covered within the first few posts.
This house is not falling down.
There is a very good chance that nothing is wrong with the house.
Dispite some intial posts regarding the straps being needed it has been shown that they are infact not. There is enough info in the thread for the op to investigate further and take action if needed.

AckwelFoley

Houses dont fall down in the literal sence anyways. The worst that can happen is well explained by ircoha..




**** < meah cant say it either

pearly20

Hi all who replied and thanks for doing so. Quick update to say that my structural engineer maintains the house is fine without the straps...he spoke to the builder about it and is happy enough. As I dont really understand the technicalities (I tried, really I did!), I have to trust he knows what he is talking about...Thanks again guys.

muffler

pearly20 wrote: »

Hi all who replied and thanks for doing so. Quick update to say that my structural engineer maintains the house is fine without the straps...he spoke to the builder about it and is happy enough. As I dont really understand the technicalities (I tried, really I did!), I have to trust he knows what he is talking about...Thanks again guys.

I told you so

And Im not immune (yet) to brown envelopes arriving in the post

sinnerboy

A4 , A5?

Depends on what he wants to cover!

muffler

A1 lads, A1

smashey

You're covering your ar$e then.

AckwelFoley

i will accept cake.