The dress rules for visiting the Grand Palace or the Temple of the Emerald Buddha are applied strictly, so make sure you do NOT wear sandals, slippers or open shoes, short pants (must cover till ankles), navel-exposing tops, sleeveless blouses and Ts.
There is a check point with guards to keep an eye on visitors approaching.
My sister from UK didn't believe it would be strictly enforced until we were actually there.
Those not dressed appropriately can borrow clothes and shoes but each item costs a 100 baht deposit and the queue to borrow can be long. When we were there at midday on a Monday, they had run out of clothes for hire for a while.
It would be better if you should just take along a light sleeved top and a loose cotton pant (remember ankle length) which you can put over your "less appropriate" clothes in a public toilet rather than wear something sweaty just returned by someone else.
The toilet facilities are after the check point, so you will have to use one elsewhere.
Went to Bangkok with my 19 year old blonde daughter - leaving husband at home. After all of his talk about the politeness of Thai people, and the need for dressing modestly, I learned that these young males are just like any other red blooded males in the world! She always dressed modestly - well, in shorts and T-shirts - nothing at all which might be perceived as immodest by our standards. She actually felt uncomfortable many times in the street and markets - groups of young males catcalling, Thai, Chinese and Indian men - some of whom were glared at by the "mama" to little avail. To some, I just smiled, nodded and said "she's beautiful isn't she?!", which had little effect either. Its very nice to be appreciated, but it was really quite uncomfortable.
The males did not have the open visual enjoyment to themselves - many ladies of varying ages complimented her on her attractiveness.
Not that offense was really taken most of the time - but I wondered if the girls should seriously consider wearing a bandana for subsequent trips. I have heard about blonde appreciation around the world - but this was somewhat over the top.
Interestingly, when we returned as a family, there was no such open male sound effects in the presence of my husband. Little did they know that I am so much scarier than he is!
Most temple frown upon visitors wearing skimpy blouses so be sure to bring along a shawl or an overblouse you can easily slip on before entering the temples. But the courtyards in this temple complexes are not subject to strict dress code.
On the territory where Grand Palace is situated you must follow the rules concerning clothes to wear - your top must be with sleeves, no shorts, no mini, and your shoes must cover all your foot - no bare heels. If you violate this rule you may be not allowed to the territory.
Although Thais are very tolerant especially to foreign tourists, it is best to show respect in dress code when visiting temples.
This dress code is strictly enforced at the Grand Palace. But do not dispair, being tourist friendly, you can rent long loose pants for guys, long wraps and cover ups for gals. Of course, you will be charged for rental.
If you are visiting many similar places, may as well buy one Thai outfit and keep it as a souvenir. If there is a large crowd, then you will waste some time queueing to rent and queueing to return.
Before entering The Grand Palace, there is quite a long list of things NOT TO DO. Here it is ~ enlarge it :-)
Do you see me taking the photo ??? :-p