Removing Section of Joists

[PaulS86]

House previously had a separate garage to the house, previous owner built a roof spanning from the house over garage (5 years on and I am still unsure what the purpose was )

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Anyway, there are two Velux windows that provide light in the newly created hallway. My issue is that the joists are in the way and still run through the middle of them.

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I cannot see the issue removing the sections of joists (obviously secure them first), and sistering two sections of timber and creating something like the following.

Any ideas/solutions and concerns would be appreciated.

[dewaltdisney]

I think that as a start you have to try to visualise the loading on the joists. To me, it looks like the roof weight is supported mainly by the rafters fixed to the house wall and footed into the parapet of the garage. Of course they will be tied into the joists and the wall but I suspect the load is not supported entirely by the traditional braced triangle. This might suggest that cutting out the obstructive section of two joists should not cause an issue.It does look messy and I think i would look to create two light well boxes under the velux windows to meet an overboarded passage way ceiling to neaten it up.

Howver, as this is structural I think you woud be required to notify this alteration to building control who might ask for stuctural calculations. It would be best to do it the right way as these sort of things might come back to bite you in the arse when you sell.

DWD

[big-all]

as dwd says you need to get your head round the construction
i would personally expose the timbers forming the roof as these may be undersized or badly supported and the weight fully sitting on the square timbers with little or no actual fixings to the wall at roof height
try tapping on the square vertical timbers near the wall with a hammer and if they are heavy loaded the will sound tight and drum like or loose and almost xylophone like

[PaulS86]

Thank you both, much appreciated. I do have the details for an engineer we previously used, phone call for tomorrow.

The first picture is the roof space, but towards the end of the corridor.

The square 2x2 seems to have been used to box in the drain pipe etc. There is currently t+g fixed to it, i'll remove it and try again with the hammer.

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[dewaltdisney]

That roof looks well supported. My guess is that the trusses are fixed to the joists that come back to the house flank wall. My thought is that the parapet wall is providing some support to the trusses and this will give temporary support while the job is done. However, I think that it is well worth getting a professional view and follow his advice.

DWD