Working with your Architect to get your ideas and needs into actual drawings. I'll walk you through on considerations that you need while designing the plans, considerations while picking your contractors during the tender process and some of my personal thoughts.

Journey

I want to make this essentially a living blog post. As I'm going along this journey. I will update this post in-line so that it will benefit future readers

Once again, I am approaching this as someone brand new to building a house. A lot of the considerations were researched upon and just relying on my own common sense and trying to visualize in my mind if something works or not.

Getting Started

In the "traditional" option that I went with, there are typically a few more professionals that you need to appoint in a project. I believe that they are the following:

1. Architect
2. Quantity Surveyor (QS)
3. Structural Engineer
4. Land Surveyor
5. Asbestos Surveyor
6. Interior Designer
7. Resident Engineer / Resident Technical Officer (RE/RTO)
8. Mechanical & Electrical Engineer (M&E)

There are more professionals that you need in your project, but these people are usually under the main contractor, e.g., Licensed Electrical Worker (LEW), Plumbers, Carpenters, etc.

Since the architect is essentially my first point of contact, he recommended the structural engineer, land surveyor and quantity surveyor to me. The prices were pretty competitive, so I decided to go ahead with his recommendations.

I had found a more affordable Asbestos Surveyor to do the site survey and removal, so I went with my own option instead.

As for an interior designer, their responsibility is towards the internal look and feel of the spaces. You can think of their role here in the same way as you would for a brand new HDB BTO flat. HDB has given you the flat with the tiles, plumbing, electrical wiring, etc. all done. This is the same standard that the architect needs to deliver the house to you; however, you are basically acting in the capacity of "HDB" to direct your architect to use the tiles, switches, etc. that you've picked. Unless you really need a specific look and feel and proposals, you could get by without an interior designer. I opted not to have one, I guess the drawback is that I won't have internal renders of the house.

The structural engineer that I engaged did not have specific recommendations for an RE/RTO, so I had to look for my own. The RE/RTO role here is to supervise the contractor when they are building the structure of the house to ensure that the contractor does not deviate from the approved structural plans. E.g., concrete that they are using has to have a certain level of consistency. I felt that it made more sense to independently engage an RE/RTO rather than rely on the recommendations of my architect or structural engineer as this provides an independent opinion without an avenue for bias. The structural component is the most important part of the house, and it has to be done strictly to the drawings and no corners can be cut.

M&E engineers typically get involved when you have complex air conditioning requirements, or you have a lot of ducting that you need to run. I chose to go with a mini-split air conditioning system, but to be honest, I am still deciding if I should install a VRV system instead.

Architectural Drawings

After I appointed my architect, I worked with him to revise the architectural drawings, and we had 5 revisions in 1.5 months before we proceeded to submit the first set to URA for approval. My architect did the submissions to URA, and I had to pay for the Planning Permission Fee which is $6,000.

During the process of revising the drawings, the architect should be the one advising you on how to best design a floor plan and what to take note of. Typically, there is a concept for every house. My concept was a multi-generational family home. This meant that each level should be its own mini-apartment of sorts where if you wanted to stay up there, you had all the things you need without having to go to level 1 to get it. E.g., fridge, washing machine, dryer, pantry.

Here's some advice that I can give when designing the floor plan for the home:

1. Ensure you know the placement of the toilets, sink and showerheads. Most of my toilets are rectangular instead of square, so typically the sink, toilet and shower area are all aligned to one of the long edges of the bathroom. However, if the bathroom is beside another room, and you haven't decided what to use that room for, it might be better to leave the connecting wall empty instead. E.g., If you place the fixtures on the right side of the wall, you won't be able to demolish or make an entryway on the right side of the wall as that would mean you would have to redo all the plumbing.
2. All bathrooms MUST be connected to an external wall of the house. If the bathrooms are not connected to the house, essentially you must run ducting to have ventilation for the bathroom. I did not want ducting as it's just another item that can potentially get damaged, or you have to clean/replace them
3. Consider having optional en-suite layouts so that you can reduce the number of bathrooms in the house. Some architects may tell you that all bedrooms have en-suite toilets these days. If your land size is big, I guess that's fine, but if not, why are you making your bathrooms the size of condominium toilets when you can just build a bigger toilet and have it shared. I feel like there is a need to have a balance here.
4. Ad an Electrical/Network service shaft/riser in the house, you can probably do this beside the lift as you would want a continuous way up to the top floor. If you don't have this, the electrical distribution box and networking equipment would just be placed in some random bedroom/room in the house. That will be hard to repair/access while inconveniencing the person using the room as long as it's not fixed. It should be located in a corridor where it can be accessible without disrupting the bedroom spaces.
5. Consider if you have space for a small utilities room that the electrical/network/solar/lift control panels can be centralized on level 1, this will speed up any kind of troubleshooting that needs to happen.
6. Consider the living situation of whom the space is intended for. Since my concept is for a multi-generational home, the first level is intended for the "old" folks, so the first level would have to be the most accessible. This includes wider corridors, wider bathroom doors and bigger bathrooms. I made provisions to the large bedroom intended for my parents to be able to be split into two in the near future if we intended to. Sometimes when the folks get older, they tend to want to have their own space, so I've made provisions for that.
7. RC Ledges for your aircon compressors, water heater tanks, etc. so you don't consume the "livable" space. RC ledges are allowed to be extended up to 1 metre to the boundary line. You want to avoid putting anything on the roof as you should maximize all available roof space for Solar Panels.
8. Consider if you really need a false ceiling or recessed wiring/plumbing for everything. Most people likely won't agree with me on this point, but to us, this allows one to maintain the house without incurring significant repair costs in the future. If the wiring and plumbing are recessed, every time you want to access/fix the issue, you will have to tear down the wall, fix it and then patch it back up. If your walls are tiled, that's even worse because you will have to keep spare tiles of the same batch, otherwise there will be color differences. There are ways that we can camouflage the trunking or even have the trunkings/pipes be part of the design feel of the house. False ceilings usually reduce the ceiling height by 50 centimetres, but on my attic floor it reduced from 3.5 metres to 2.4 metres, which is a whopping 1.1 metres that made it even lower than HDB ceilings. I opted to not have any false ceilings throughout the whole house. All our electrical wiring and plumbing are to be exposed over the wall and not recessed. We may box up, e.g., the main sewer pipe or specific areas of the ceiling, but the majority of it should be in the open.
9. Not having planters. Initially, I was trying to understand what the point of planters was. My architect said that it's a space to put plants it to soften the look of the house. To me, it's basically a permanent pot made of concrete. The planters were located on the OUTSIDE of the railings. How would you be able to maintain that? Climb over the railing and top up soil/replace the plant? That doesn't make sense at all. I opted to use the space for a full deck area which I'll eventually just be putting some potted plants on it to achieve a similar effect
10. Consider wrap around balconies, if you're intending to have balconies, and they aren't connected all the way around, why not just connect them? You could always add a door or something else to restrict access if you would like, but if they aren't connected at all in the first place, it would be even more trouble to fix that
11. Private room staircases can be a nice and luxurious thing to have, architects would typically recommend a spiral staircase to save space as installing traditional stairs would take up the same space as your main staircase based on BCA requirements. That being said, the staircases take up a lot of space on both floors regardless. Can you take advantage of perhaps the lift or main staircase and have that double as your private staircase? Perhaps adding a door at the stairs or lift corridor, or have access card restrictions in the lift.

Tender/Construction Drawings

In the tender/construction drawings, there will be a lot of pages in there that you will likely be overwhelmed by. Here are some suggestions for the tender drawings:

1. Pay attention to the room dimensions and if there is enough space for what the room is for, e.g. bathroom, bedroom.
2. Check corridor and bathroom dimensions if the bathroom needs to be wheelchair-accessible, there are accessibility guidelines from BCA for this, some of which you can find in my first post.

My architect was the one who did the main bulk of work for the tender drawings, and when I asked for changes, he said we could do it in the construction drawings. I think this was done to be expedient as the tendering process takes time as well. What I would emphasize is that as the tendering process is going on, and you're deciding on a contractor to go with, study the tender drawings. Particularly the following sections

1. Floor/Wall/Ceiling/Skirting Materials and Finishing, if you want larger format tiles, e.g., to reduce grout, or you want some other specific layout
2. Size/Style of Windows/Doors, toilet windows should be top hung windows. Three panel doors could be reduced to two panel doors to save costs, excessive windows/doors in a room that will already have a lot of natural lighting
3. Position of Ceiling/Wall Lighting Points and Electrical Switches, try to envision how you will be using the space and where the switches should be positioned, e.g. if you are coming up the stairs, and you have a long corridor, you would turn on the lights and turn off the lights once you're entering a space, the switches should be positioned to allow you to do that
4. Position of Air-con units, do you have to have wall mounted units, or they have to be ceiling units
5. Position of Ceiling fan points
6. Position of PowerPoint sockets
7. Height of Ceiling Boards
8. Bathroom Glass Doors
9. Position of Water Inlet/Outlet points

Working with your Architect

I had been trying to form an opinion back and forth on who should be doing the "work" of getting the drawings out. Sometimes I would try to explain a concept to my architect, but they wouldn't understand what I was trying to say. This ended up with me having to draw on either a piece of paper or an initial render I did in sweethome3d to be able to convey what I wanted.

I have a bias for action and drawings were the easiest way to communicate what I wanted. I think you have to accept that the shortest and clearest route possible is for you to sketch it up and send it over to them.

Tendering

Once the submission to URA has achieved written permission, your architect will work with the QS to prepare the tender drawings and documents. Once that is done, the QS will be the one inviting the contractors to come bid on your project. Typically, the architect and QS may make some recommendations, but you can source your own contractors as well to be included in the tender. The contractors will be given a few weeks to respond to the tender, and once the submissions come back, the QS will do tabulation to compare the different prices that have been quoted.

Here's the part where it gets a little tricky, and these are my observations about the tendering process:

1. Some of them don't provide a breakdown of the costs, e.g., per square feet, and instead provide a lump sum cost, you have to push them to provide a breakdown for you as even within the tender itself, the prices can still be pretty opaque
2. The contractors think of the jobs differently and end up shifting cost from one section to another. This makes trying to compare between the contractors extremely difficult
3. Labour and material costs are not separated out, so you don't know how much they are charging for labor
4. Painting is all lumped into one section, and there's no specificity on the type of paint that will be used internally or externally
5. Air conditioning doesn't come with the proposed brand/specs, thickness of insulation
6. Electrical/Plumbing doesn't come with detailed specs about what type of pipes they are using, e.g., stainless steel, pvc or copper, does the price include water tanks as well as pumps?

Independent Quotes

Let's assume that you've appointed a main contractor. You don't have to rely on everything the main contractor has quoted you unless you don't want to spend the time to do some independent research. When a contractor takes over a site, they will be liable for anything that happens onto the site. If you bring in your own vendor, there typically is a profit and participation amount that you will have to pay to the contractor. Some works don't have to be done when the contractor has control over a site, e.g., solar can be done after TOP or CSC. For others, an independent quote can be less expensive than what the main contractor has quoted you even after factoring P&P. Spend time to do your own research into your own vendors.

Frustrations

One thing that frustrates me the most is when prices come back without GST being included. Even though IRAS practices around GST clearly state that prices must include GST, it is almost always not included. Please remember to check if the professional or vendor you are engaging charges GST and take that into consideration when negotiating discounts.