is this crack anything to worry about?

[ukes]

Made you all look

Right guys, after a bit of savvy info if anyone could help.

Im currently having my roof done on a 110 year old end terrace. As i currently only have two beds im toying with the idea of a loft conversation but before i even look into it any further and get an engineer in to asess the load baring capabilities of joist etc im wondering if i'll be opening a massive can of worms.

Ive lived here 10 years and never had cracks in walls or anything. The surveyor that did the survey when i brought the house said these houses moved in the first 30 years but are as structurally sound as anything else.

The image is the wall adjoining next doors propery as opposed to the end obviously. You will also notice that the purlin on the second image to the outside wall is basically sat on one brick, im assuming that was common practice back then but how would it be viewed by a strucural engineer?

Thoughts please

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• 8 Apr 2014
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[KenGMac]

ukes, Hi.

A question please.

Are there any indications in the room below, on the party wall of a crack that may have been filled in historically, try using a bright torch beam with the torch body held parallel to the wall and let the beam of the torch floor sideways over the wall in the room. Any old filled cracks should show up.

From what can be seen from the photos, it appears that the load from the Purlin has caused the section of the party wall below the Purlin to rotate outward towards the front [or rear] gable wall, it seems from the photo that the area of wall that appears to have rotated as can be seen if you line up the brick beds between the rotated area of brick and the remaining section of brick on the wall.

It is almost as if something has historically impacted with the roof? or some off the wall thinking a bomb blast during the last war, OK a long shot but.

Would be interested in an answer to the question posed.

Suggest you have a look at the Helifix / Helibar web site that could be a solution if the wall is still rotating, there is a very substantial crack below the purlin

Ken

 

[ukes]

Hi Ken

Its a strange one isnt it. When i moved in the "plaster " was of a rough nature, more sand and cement than todays mix. There was nothing evident then and nothing 10 years later. The purlin obviosly sits inbound of the wall so im unable to ascertain wether it rests on the party wall or extends through to next door. I could ask if i could have a gander up their loft and see if theres is the same. The house dooes appear to lean slightly towards the left hand side of that picture and always has.

Im assuming it moved in its formative years asvthe front side of the properties were apparently built on clay. Im certain if any movement had occured since i moved in we would have had crackss of some kind, i know the guy that owned it before me and he never encountered cracking either.

My main worry is getting a structual engineer to look at the feasability of a loft conversation and this issue will open a can of worms.

 

[ban-all-sheds]

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• ukes
• 8 Apr 2014
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Are those roots in the top right?

 

[ukes]

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• ukes
• 8 Apr 2014
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Are those roots in the top right?

No bud. Its basically crap thats been disturbed from having the slates removed, Its broken nesting material from birds I think.

Id probably be more worried about roots at the top of a chimney stack than this crack to be fair

 

[ban-all-sheds]

Indeed, but can't see in the photo where they are coming from.

 

[bernardgreen]

That looks like roof spread and needs to be checked. The rafters move outwards until they no longer rest on the top of the wall.

While the roof may have survived so far a heavy fall of snow could add enough weight to cause the spread to increase with a possible collapse of the roof.

The repair is very simple. horizontal tie beams across the roof to stop the rafters moving apart.

 

[ukes]

That looks like roof spread and needs to be checked. The rafters move outwards until they no longer rest on the top of the wall.

While the roof may have survived so far a heavy fall of snow could add enough weight to cause the spread to increase with a possible collapse of the roof.

The repair is very simple. horizontal tie beams across the roof to stop the rafters moving apart.

Thanks Bernard

Just explain because Im not that savvy with roofs.

When you say the rafters have moved, do you mean spread apart?

If so is it possible that that could have done this? Im assuming the rafters are fixed to the purlin? Its obvious the purlin has not moved because its still sat on the brick on the gable wall.

 

[KenGMac]

ukes, Hi again.

Exactly that, because if the ceiling joists are not attached to the rafters, it means that the rafters can very, very slowly over a long time.

The rafters impose a huge downward and outward force on to a piece of timber [called a wall plate] the wall plate is fixed to the top of the wall quite simply the forces that the rafters exert physically push the wall plate and wall outwards.

The load on the rafter is a composite of, the weight of the tiles [or slate] the action of wind, the weight of rain water, and then the weight of any Snow load, the action of wind is considerable as is at times the weight of Snow / ice

The way around this problem is to make the roof rafters into a triangle the fixing of a ceiling tie that supports the ceilings in the various rooms and at the same time is firmly fixed to the individual rafters, in effect if you think about it a triangulation is being formed, which is an extremely robust strong structure provided the design incorporates cross bracing [ a description of which is not needed in this context]

As an aside, the purlin will in effect follow the rafters and in effect be dragged out of position. this effect will possibly pull the wall below the purlin out of position thus causing a fairly large crack.

Getting back to your original post? the crack below the purlin bearing point is historic, because there are no indications in the room below of any recent cracking, it could be that there is no recent movement to speak of.

Any chance of a photo of the rafters where they meet the wall head?

 

[ukes]

Hi Ken, thats become a bit clearer (although im still struggling to understand how bracing the rafter will stop the problem, or in this case reduce any potential).....ill have a think and im sure it will come to me!!!!

When you say where the rafters meet the wall head do you mean where they meet the outer wall of the house, as in where the outside of the rafters sit?

Excuse my ignorance

 

[ukes]

Hi Ken, thats become a bit clearer (although im still struggling to understand how bracing the rafter will stop the problem, or in this case reduce any potential).....ill have a think and im sure it will come to me!!!!

When you say where the rafters meet the wall head do you mean where they meet the outer wall of the house, as in where the outside of the rafters sit?

Excuse my ignorance

Edit, I think I know re bracing. You mean horizontal bracing from the affected side rafters to the opposite side, underneath the apex?