upstairs floor joists in old cottage

[mordzy]

Hi there,

I am currently (and slowly) renovating an old grade 2 listed cottage and have just taken out the old bathroom to fit a new. i have taken the floor up to re locate water pipes etc and i notice the joists seem small though i may be wrong?

house is a 2 bed and small. there are two 8"x2" beams that run through the house and the joists then run in the opposit direction on top of the beams as expected however the joists are only 3" deep, which im not sure is unusual/wrong/unsafe. the only reason i think this is that i recall in a previous house having more space under the floor to work.

Please could someone confirm.

the floor / house is what id call charter in that like an old cottage the floors are not level. when it was purchased i had a full survey which didnt show up anything other than early 'settlement' which was 'normal' for a stone built house of the era.

Thanks

 

[AronSearle]

the joists are only 3" deep, which im not sure is unusual/wrong/unsafe

What distance are they spanning?

 

[mordzy]

id guess at stone wall->8ft->beam->4ft->beam-8ft->stone wall

ill measure accuratly when i get in and upload a drawing.

 

[mordzy]

Ok i have measured accurately.

the two beams that support the joists are 8x3.5" they are situated 6ft in from the external walls with 6ft between them also. total dimensions of floor space is 18ftx18ft with the max span being 6ft at any one span.

diagram and joist depth attached.

Untitled

• mordzy
• 22 Aug 2012
• 1

Untitled

• mordzy
• 22 Aug 2012
• 1

[/img]

 

[garyo]

That's identical to my set up (1950's semi) other than my joists are 10cm deep.

 

[xr4x4]

I was fitting joists bigger than that today on decking!!

 

[mordzy]

i know its kind of wrong by todays standards but other than when installing a bath and having to reinforce the floor should i have any worries going forward or is this acceptable for the age of the house?

it was built in Circa 1820

 

[mordzy]

anyone?

 

[tony1851]

If you are replacing the floor complete, the smaller joists should be 4x2.
The 2 big timbers would now be regarded as overspanned; an 8x4 spanning 18ft and carrying over 100sq ft of floor is too much. For this span, you need to be thinking of steel rather than timber.
But would the conservation officer allow that?

 

[mordzy]

im not actually replacing anything at the moment. i just took it up to move some wiring which had been done recently by the previous owner. should i be looking at replacing the floor anyway? i could have done without the cost.

What about building a new floor on the one above, obviously not supported by the old. the ceiling above is very high.

The problem i have is conservation wanted the supporting beams preserving

 

[tony1851]

If you're not replacing the floor, the obvious thing if fitting a bathroom in is to try and keep it near the end of the span of the main beams.
It might also be adviseable to double up the 3x2 in the bathroom area.
The floor structure would have been fine for the early 1800, when people were smaller (and lighter) and didn't have as much stuff as we do today.

 

[mordzy]

thanks for the help. The bathroom is to one of the corners so at end of span and next to external wall. my plan was also to raise the bath up on a platform made from correct size joists and tie these into the external wall

Thanks again.