Tools › User guides › Building Frame Designer
The Building Frame Designer analyses your whole house as a 3D RCC frame (like STAAD) and designs every beam, column, slab, footing and staircase to IS 456, IS 13920, IS 1893 and IS 875. This guide explains every box on the page, step by step, and how to read the results.
Open the Building Frame Designer › Quick start
12'6", 10, 11'3" or 4, 3.5, 4) and press Update grid.| Field | What to enter | Typical value | Tip |
|---|---|---|---|
| Units for your inputs | Metres and millimetres, or Feet and inches. | — | Only the inputs change. Results, drawings and the report are always in m and mm (IS 456 practice). Switching does not change your design. |
| Spacings along X (left → right) | Centre-to-centre distances between column lines, left to right, separated by commas. | 3 – 5 m (10 – 16 ft) | In feet you can type 12'6" or 12.5. Up to 10 bays. Lines are numbered 1, 2, 3 … |
| Spacings along Y (top → bottom) | Same, from top to bottom of the plan. | 3 – 5 m | Lines are lettered A, B, C … from the top. |
| Update grid | Press after changing spacings. | — | If the number of bays changes, columns and beams are reset to every grid point and openings, walls and stairs are cleared. |
| Tool | How to use | Typical | Tip |
|---|---|---|---|
| Columns | Tap a grid point to add or remove a column. | — | Every beam must reach a column through the beam network, otherwise you get a warning. |
| Beams | Tap a grid line between two points to add or remove a beam. | — | Beams are the same on every floor and on the plinth. A slab forms in every bay closed by beams on all four sides. |
| Slab openings | Tap a bay to leave it without a slab (duct, courtyard, lift). | — | For a staircase use the Stairs tool instead — it designs the stair too. |
| Walls | Tap a beam to change the wall on it: 230 → 115 → no wall. | Outer 230, inner 115 | Roof beams carry only the parapet. |
| Stairs | Tap a bay to place a staircase; tap it again to change it. | — | See the stair settings below. |
| Columns at every grid point / Beams on every grid line | Quick buttons to fill the whole grid. | — | Useful after changing the grid. |
| Field | What to enter | Typical value | Tip |
|---|---|---|---|
| Type | Dog-legged (2 flights), Straight flight, or Open-well (3 flights). | Dog-legged for houses | A straight flight needs a long bay (about 4.5–5 m for a 3 m storey). |
| Flights go along | X (along grid 1, 2, 3) or Y (along A, B, C). | The longer side of the bay | The arrow on the plan shows the direction going up. |
| First flight starts from | Which grid line the first flight starts at. | — | Flips the stair. |
| Riser (max) | Largest riser you accept. | 150 – 170 mm (6 – 6.5 in) | NBC limit for houses is 190 mm. The tool divides the storey height into equal risers not above this. |
| Tread | Going of each step. | 250 – 300 mm (10 – 12 in) | |
| Flight width | Clear width of each flight. 0 = fit the bay. | 0.9 – 1.2 m | Under 0.9 m gives a warning (NBC minimum for houses). |
| Stair goes up to the roof | Tick if a mumty (stair cover room) is built on the roof. | Ticked | Adds 115 mm walls 2.4 m high and a 120 mm roof slab over the stair. |
The stair bay gets no floor slab. Its flights and landings are designed as waist slabs (IS 456 cl 33) with live load 3 kN/m² (IS 875 Part 2), and their load goes to the beams around the bay and, through a landing beam, to the columns.
Under Your plan drawing (optional), upload a photo, scan or screenshot of your house plan (JPG or PNG; for a PDF take a screenshot first). It stays on your device and shows under the grid. Then:
| Field | What to enter | Typical value | Tip |
|---|---|---|---|
| Image width | Real width of the picture. | — | Set by “Set scale”; you can also type it. |
| Opacity | How strongly the drawing shows. | 0.4 – 0.7 | |
| Shift right / Shift down | Moves the picture under the grid. | — | Fine alignment after “Make grid”. |
| Fit image to grid / Remove image | Quick buttons. | — |
If columns stand on the plot boundary, their footings cannot spread outside it. In the Plot boundary box choose each side that is on the boundary (Left = line 1, Right = last number, Top = line A, Bottom = last letter). The column face and the footing edge are kept flush with the boundary line.
| Choice | What happens | Note |
|---|---|---|
| Not boundary | Normal isolated footing centred under the column. | — |
| Strap footing (recommended) | A strap beam at footing level ties the boundary footing to the next column inside. It carries the off-centre moment, so the soil pressure stays even. The tool designs the strap beam (size, steel, stirrups) and adds it to the BBS. | Needs a column further in on the same grid line. |
| Eccentric footing | No strap. The column below the plinth and the plinth beams carry the moment P × e, so they need more steel. | Plinth beams must be on. |
| Field | What to enter | Typical value | Tip |
|---|---|---|---|
| Number of storeys above plinth | 1 (ground only) to 5 (G+4). | 2 (G+1) | A height box appears for each storey. |
| Floor heights | Floor-to-floor height of each storey. | 3.0 m (10 ft) | Ground-floor height is measured from the plinth. Allowed 2.4 – 6 m. |
| Plinth height above ground | Top of plinth beam above ground level. | 0.45 – 0.6 m | |
| Top of footing below ground | Depth of the footing top below ground. | 1.2 – 1.5 m | The footing thickness is added below this. |
| Plinth beams (tie beams at plinth level) | Tick to tie the columns at plinth level. | Ticked | Needed for soft soil and for eccentric boundary footings. |
| Concrete grade / steel grade | M20 – M30, Fe 415 / Fe 500. | M25, Fe 500 | IS 456 Table 5: M25 minimum for moderate exposure. |
| Exposure | Mild or Moderate. | Moderate | Sets the cover: 20 / 30 mm for beams and slabs. |
| Starting member sizes | Column, beam, plinth beam sizes and slab thickness. | Column 300×300, beam 230×400, slab 125 | With auto-size on, failing members grow in 50 mm steps until they pass. |
| Auto-size members | Tick to let the tool enlarge failing members. | Ticked | Untick to check your own fixed sizes. |
| Field | What to enter | Typical value | Tip |
|---|---|---|---|
| Live load — floor / roof | IS 875 Part 2. | 2.0 / 1.5 kN/m² | Residential floors 2.0; accessible roof 1.5. |
| Floor finish — floor / roof | Tiles, screed, waterproofing. | 1.0 / 1.5 kN/m² | |
| Masonry unit weight | Brick masonry. | 19 – 20 kN/m³ | Fly-ash bricks / AAC blocks are lighter (AAC about 7). |
| Openings in walls | Doors and windows as % of wall area. | 15 – 25 % | |
| Parapet height / thickness | Roof parapet. | 1.0 m / 115 mm | |
| Safe bearing capacity of soil | From the soil test report (Foundation section). | 100 – 200 kN/m² | Use our SBC calculator if you have a borehole log. |
| Seismic zone | IS 1893 Part 1:2016 zone map. | III | Most of South Bengal is Zone III; North Bengal IV / V. |
| Soil type | I rock / hard, II medium, III soft. | II | Soft soil: no bearing increase under earthquake. |
| Importance factor | 1.0 residential, 1.2 more than 200 occupants, 1.5 important building. | 1.0 | |
| Frame type | SMRF (R = 5, ductile detailing to IS 13920) or OMRF (R = 3). | SMRF | Zones III–V should use SMRF. |
| Masonry infill walls | Tick if brick infill is built in the frame. | Ticked | Uses T = 0.09h/√d for the period. |
| Basic wind speed Vb | IS 875 Part 3 Annex A for your town. | Kolkata 50 m/s | |
| Terrain category | 1 open land … 4 dense city. | 2 | |
| Force coefficient Cf | Wind force coefficient for the building. | 1.2 |
After Analyse & design, the results show (all free on screen):
At the bottom of the results, open Input sheet for RCC Estimator Pro. It lists every input of RCC Estimator Pro in the same order as its form, with the value from your design. Rows marked “Input to be done separately” (doors, windows, bricks, plaster, tiles, rates…) are not worked out here. Where members differ, the most common size and steel are given.
Everything is free to view. To print or save the complete design report (design basis, loads, every member, footings, stairs, BBS, quantities and the RCC Estimator input sheet) press Print / PDF report and pay ₹49 for that design. Keep the receipt code: it unlocks the same design on another device. Changing any input makes it a new design.
Yes. All analysis, design, drawings and the bar bending schedule are free on screen. Only the printable PDF report costs ₹49 per design.
Yes. Choose “Feet and inches” in Units for your inputs. Grid spacings accept 12'6" or 12.5; member sizes are in inches. Results stay in metres and millimetres.
In the Plot boundary box choose Strap footing (recommended) or Eccentric footing for that side. The footing is kept flush with the boundary and designed for the eccentric load.
No. It is an engineering aid for regular RCC frames. Have the design checked and signed by a qualified engineer before construction.