323415967-6-Floors-Upper-Floor-of-Timber-1.pdf

Good notes

1. Types of Upper Floors:
Based on materials used for
construction:
Depending upon the materials used for construction and upon the
arrangement of beams, girders etc. for supporting the flooring upper
floors are classified as:
1.R.C.C. Floors
2.Steel joist and stone or precast floors
3.Jack Arch floors (brick and Girder Cement Concrete Floor)
4.Filler Joists Floors
5.Precast Concrete Floors
6.Timber Floors

2. 6.Timber floors
•Found in earlier construction
•Costly( Except at those locations where local timber is cheaply
available)
•Fire Poor resistance
•Highly vulnerable to termite
•Light in weight
•Sound insulation
Timber floors are basically of three types:
A.Single Joist Timber Floors
B. Double Joist Timber floors
C. Framed or Triple Joist timber Floors

3. A.Single Joist Timber Floors
•Simple type of timber floor
•Used for short span mainly for residential bldgs.
•Span up to 4 mt.
•For lighter load

4. •Theendofthejoistsarenailed,coggedornotchedtothewallplates.
•Ifthejoistsofadjacentroomruninthesamedirection,theymaybe
overlappedandnailedtoeachother.
•Plankingconsistsofwoodenboardsof4cmthickand10to15cm
width,whicharefixedtothebridgingjoists.
Single Joist Timber Floors

6. B.Double Joist Floor
•Stronger Floors
•Used for span between 3.5 to 7.5

7. •The bridging joist are supported on intermediate wooden support
known as binders
•Loads of bridging joist are transferred to the binders and through them
to the end walls
•Because of intermediate supports the bridging joist are of smaller
sections
•Joist are spaced at 30 cm centres
Double joist floor

8. •Spacingofbindersiskeptat2to3.5.
•Bindersrestonstoneorwoodentemplates.
•Toreducethedepthoffloorsbridgingjoistarecoggedtothebinders.
•Endsofbridginggirdersarecutandjointwithhelpoffillersprovided
alongthetwosidesofwalls.
Double Joist Floor

12. C.Triple or framed joist floor
•Floorissuitableforspansgreaterthen7.5mt.
•Intermediatesupportknownasgirdersareprovidedforthe
binders
•Elements for flooring
1.Floorboards
2.Bridging joist
3.Binders
4.Girders

13. Triple or framed joist floor

14. Triple or framed joist floor
•Bridgingjoistsupportsthefloorboards
•Thebindersarestaggeredandconnectedtogirderstoincreasethe
rigidityofthefloortodecreasetheoveralldepthoffloors
•Sometimesgirdersarereplacedbyrolledsteeljoists

19. Single Joist Timber
Floor
Double Joist Timber
Floor
Triple Joist Timber
Floor
1 Simple type of timber
floor
Stronger Floors VeryStrong Floor
2 Span up to 4 metersUsed for span between 3.5
to 7.5 meters
suitable for spans greater
then 7.5 meters.
3 Element
1.Floorboards
2.Bridging joist
Elements
1.Floorboards
2.Bridging joist
3.Binders
Elements
1.Floorboards
2.Bridging joist
3.Binders
4.Girders
Comparison of all three Timber floors: